thanks DjLizard for your explaination...
beside the amount of RAM, some other issues might slow down your computer system... like having malware crawling around in your system... lesser hard disk space... fragmented files...and even some system configuration can slow down system performance... there are just too many issues about it...
well... i think you might want to ask Compaq themselves...
actually depend on the usage of the system... if you are using a lot of high end programs, such as graphic editing, 3D graphic editing, you might want to get more RAM... even up to giga-byte... but i recommend having 512MB of RAM if running Windows XP machine... but is really up to you...
but before you get any additional RAM, make sure you know the maximum amount of RAM (and the maximum size) your main board can support...