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So you've finally decided to buy an external hard drive as a backup option for your computer. This is a great choice for you because you're making backing up your data faster and easier than you could ever have imagined. You're also making your data far more portable in larger quantities than before.

You'll no longer be limited to storing a few hundred megabytes or even several gigabytes. Nope. Now you can look forward to portable and reliable storage capacities ranging into terabytes. That frustrating desktop computer or network file server backup job just got a whole lot easier.

If you've never bought an external hard disk before then there's a few pointers here that may help to have on your shopping list before you go and make that final purchase.

1. Buy A Brand
Do yourself a huge favor and buy a brand name that you easily recognize. Sure these may cost a little more than brand x but with computer accessories like this you really do get what you pay for. If a Western Digital 100GB external drive costs $200 and another brand x 100GB drive costs $80 why do you think that is? Because the company likes you? Because they like making smaller profits? No it's because it's a cheaper drive made with inferior parts that's going to break a lot sooner than you might expect.

The other aspect of sticking with a brand is your warranty. For example Maxtor, Western Digital and Iomega are all reliable companies and well known for their external hard disks. If something goes wrong with your drive you can have it fixed. With brand x you'll probably not even be able to find an email address that you can contact the parent company on. Is saving a few dollars worth that risk?

2. Google It
Whatever brand or model you decide on make sure you do some research before purchasing. Always, always Google the exact brand and model of the drive you're considering buying. Look for reviews and especially any feedback on how reliable a drive is. You'll be very surprised to find that some companies have particularly bad reputations in terms of equipment reliability and what's known as the "click of death" in the external hard drive industry.

Spend time in Google checking out your prospective purchase. You'll be glad that you did.

3. Connectivity
When it comes to external hard drives you'll need to choose carefully when selecting your connection types. Your external hard drive will support either USB or Firewire. Firewire is the fastest option available at the moment but your computer may not support this. The vast majority of modern computers will, however, feature a USB port.

The next question now is what type of USB port do you have - USB 1.0 or 2.0? If your computer only has a USB 1.0 port then your external hard drive is going to transfer data VERY slowly. USB 2.0 is the minimum you should consider as connection options for both your computer and your external hard drive. If you don't have a USB 2.0 port (also called HiSpeed USB) on your computer you may need to get a USB 2.0 card fitted.

4. Speed
Now of course we need to talk about speed. The faster your hard drive operates the faster data will get transferred to your computer and vice versa. Without boggling you with comptuer jargon there's a couple of technical things you need to include on your shopping list.

Seek time - this needs to be 10ms (milliseconds) or less

Buffer size - more is better. Get a drive with at least a 4MB buffer.

RPM - higher is better. 5400rpm as a minimum. 7200rpm being preferred.

Stick to the above basic pointers and you'll do just fine.

5. Size
This is the simple part of the whole "buying an external hard drive" equation. Buy as much as you can afford. If you can afford 100GB then get it. However if you can afford 200GB then get it. Then again if you scraped together a few dollars more you could afford 300GB then do it.

This isn't a sales pitch. Far from it. There is simply no such thing as having too much data storage space. The 160GB drive that I have here was filled up in a little under a month. Currently a terabye option sounds good for my future needs.

Always add 50% to your data storage requirements. Honestly. You'll thanks yourself within the first 90 days of buying your external drive.

Hopefully now you'll be better prepared for purchasing your new external hard drive. It's one of the best purchases you'll ever make.

Looking for the best external hard drive? Visit BackupAdvice.com for more information on your options.

Each camera had its own monitor. One camera, one monitor.

CCTV systems were introduced in the US and the UK during the 60s and 70s.

CCTV systems are over a thousand times more advanced than the basic camera and monitor configurations that first appeared in the 1960s. Systems from the 60s were basic, consisting of very low resolution black and white cameras connected by coaxial cable. Each camera was connected to a black and white monitor. A 16 camera configuration required 16 monitors. New applications of camera security systems include: underground trains and stations, sports stadiums, retail stores, shopping centers, public facilities, community parks, garages and parking lots.

CCTV Technology Evolution The basic technology evolved in the 60s. First of all, cctv switch boxes were added. A switchbox would allow the operator to switch between cameras. Operators now could see multiple camera views on one monitor. Only one camera could be viewed at a time. The 70's brought Multiplexers, VCRs and solid state cameras. Multiplexers allowed the screen to be broken into multiple frames on the same monitor. VCRs allowed easy recording and video distribution. Solid state cameras helped improve reliability and the integration of VCRs.

'First generation' CCTV technology was initially impeded by some fairly major performance related problems.

In the 80s we learned that VCR recorders had many problems. VCR recorders were temperamental. The quality of the recordings was very poor. The combination of low resolution camera images, poor quality video tapes and low tech solutions meant that grainy and unclear images couldn't be relied on even for conclusive identification purposes.

VCR technology couldn't allow the operator to review and record events simultaneously and it was a very time consuming process to find and review specific events.

There was no motion detection capability and no way of viewing events from a remote location.

Expensive for what you get Even though early CCTV systems provided only relatively basic functionality and moderate performance, they were quite expensive - both in terms of the initial equipment cost and the installation. Since this is still a new growth industry, there is still a lack of qualified and skilled installers.

The Next Generation CCTV The 'next generation' of CCTV system arrived in the mid 90s. The new technology was a computer based Digital Video Recorder (DVR) DVRs allow images to be recorded at much higher resolution than previously. DVR eliminated a major problem with first generation CCTV systems Video Tape! Worn out, forgot to change the tape, VCR recording tape.

DVRs are automatic and never require user intervention. When it is time to look at recorded images, the DVR continues to record. Images are time and date stamped and are very easy to review. DVRs using IP (Internet Protocol) technology allow authorized remote users to view, transmit two way audio, fully control the cameras and system itself over a local area network (LAN), a wide area network (WAN) or via the internet. With such flexible access, the modern generation of CCTV cameras may be operated remotely from a control center or, in fact anywhere with internet access. Equally, high quality digital images may be streamed anywhere and captured at a convenient and secure location. But it isn't only the operating platform that has developed significantly; camera technology too allows far more functionality.

Today's generation cameras can PTZ - pan, tilt and zoom, have higher resolution options, a large variety of lenses and are also capable of operating in 'night vision. Audio is also now part of CCTV DVR technology. An operator is now able to synchronize motion based video events with audio analysis. Two way audio transmission allows the operator to question possible intruders, give instructions to staff and to record/search/replay in both audio and visual form. Next generation DDTV DVR systems are compatible with earlier camera technology, and are scaleable, flexible and can be integrated with a broad range of other management systems, such as access control and building management systems.

CCTV has certainly come a long way since the 1960s; it's clear that the future of CCTV is secure and that technology will continue to develop to meet the changing needs of the surveillance market.

John Beagle is a technology writer for Camera Security Now.