Many aspects of the personal computer have increased in leaps and bounds in terms of performance and what they are capable of doing.

Computer memory, often referred to as Random Access Memory (RAM), has become of greater and greater performance as time has gone on.

One of the famous quotes from back in the eighties was one made by Bill Gates when he said that no one would ever need more than 640KB of memory. Well that has been passed for ages now, with high performance machines sometimes sporting over 1GB of it.

There are many advantages that can be had with more memory.

• Programs run faster

• Less waiting time for programs to load

• More programs can be run at a time

• Overall computer speed is increased

Double Data Rate (DDR) memory is the staple of the consumer market. It has taken off due to public demand and now comes quite reasonably priced.

Computers don't generally come with less than 256MB of memory nowadays. My computer after freshly installing Windows 2000 (no, I haven't gone to Windows XP yet) takes about 80MB or memory. That is the very least, with no additional programs or anything else installed. After I have installed all the graphics drivers, Internet connection software for ADSL, virus protection and firewall it takes around 160MB of total memory.

From my previous experience, 256MB will do, but after it becomes quickly filled when running a few programs, Windows reverts to using the hard drive for memory. It's a way to fake more memory, by using the hard drive as a temporary store. 512MB now does it for my needs, but if you run many programs or memory intensive ones, 768MB or even 1GB will do better.

But is memory size the only factor?

An equally important factor is the memory speed. It is measured in MHz. Most systems use 400MHz DDR memory. This would be the safe bet with almost any processor you may have. 400MHz has also become the most common to buy, there is not much slower than that left to buy.

Memory from a reputable manufacturer will ensure that you don't have problems with it and will also provide a certain amount of overclocking if you are into that. Even better would be to get faster memory, it just runs down at the computers speed, even if it is designed for more.

Another aspect of memory has come into play, being highlighted mostly by the enthusiastic overclocking crowd, and that's latency.

Memory is a bank or table of places where information can be stored. In order to get the specific rows and columns certain things have to be activated within the memory. In a nutshell latency refers to how long it takes to be able to acces another part of memory. The shorter the time it takes, the quicker it is.

Low latency memory comes at a huge price premium, with 512MB of top class memory costing more than some processors.

But does it actually benefit you?

If you are into high-speed 3D games then there could certainly be a difference. For the rest of us, there probably won't be much difference. It's still worth it however to keep latency in mind when shopping around. I would certainly choose a lower latency model when buying.

Dual channel memory is another recent addition to memory technology. What it does is it puts the memory into pairs, the two pairs together can increase on the performance and speed of the memory by up to 10%. The motherboard has to support it, and the memory has to be the dual channel kind. Dual channel will work even when not in a pair, but normal memory will have no advantage when put in a pair.

Finally, DDR2 is a newer addition available for Intel systems. It has 240 pins (the little copper strips at the end that plugs into the slot) as opposed to DDR memory's 184 pins. In this respect the two are completely incompatable. DDR2 is by design meant to be in pairs, they don't have to be, but they all have dual channel capability. Only Intel processors with LGA775 socket type use this memory, but it is much faster.

So, whenever looking for more memory, try to bear these factors in mind...

• Do you need DDR or DDR2 (LGA775 systems)

• What speed do you need? Usually 400MHz (named PC3200) or faster?

• 256MB minimum, preferably 512 or up to 1GB

• Dual channel pairs. Do you need them and does your computer support them?

• Latency, lower the better, but not essential. CAS of 3 is normal.