Tom's Hardware has posted a new guide to investigate how much RAM memory you really need.
How much RAM does your PC have? If you run Windows XP, it is probably in the range of 512 MB to 1 GB. Older Windows versions will do the job with less than that, but as soon as you execute demanding applications or more than one application at a time, anything below 512 MB will likely translate into performance bottlenecks.
Of course, the more RAM you have, the better off you are - but how much memory do you really need?