1. you'd better set virtual memory reasonably
Windows XP always set a big virtual memory for security default, which wastes much hard disk space. In fact, we can set it a little bit smaller to optimize system.
Enter Control Panel/System/ Advanced/ Property/ Setting/ Advanced/ Virtual memory/ Change; you can see the virtual memory setting window. Firstly, make sure which drive letter your page files are on, and then forbid all page files on other drive letter. The suggestion to set page files on other disks but not C disk (system disk) is in order to increase the speed of hard disk and therefore be good for speeding up system. According to Microsoft’s proposal, page files should be 1.5 times bigger than RAM. If you have a large RAM, the space page files taking up is significant. So, I suggest that if your RAM is below 1GB, you can set virtual memory 1.5 times with the same maximum and minimum; if RAM is from 1GB to 2GB, set it 1 time; if RAM is above 2GB, just setting it half of RAM is completely workable. What you have to notice is that if you install big games or software, you must keep a certain virtual memory because they need too much RAM.
2. I suggest that you speed up your computer by o ther ways. Like adding RAM, doing a reinstall of Window, thoroughly cleanning registry, removing junk files, stopping unnecessary and other things to optimize the whole system.
you can take a look at this article How to Optimize Window XP and Vista system? on http://www.system-tools-software.com/knowledge/how-to-optimize-windows-system.html