use your pendrives as RAM  

Many of u might be thinking that I am telling lie & those, who r using vista might be thinking that this feature is confined to vista.But, truth is something different.This software is not free if u purchase vista than u get Microsoft ready boost software free but there is 3rd party software for XP.It is eboostr.Here is the screenshot
eBoostr™ is an alternative solution to Vista’s ReadyBoost and SuperFetch technologies now available on Windows XP
It speeds up your PC and improves application responsiveness by using flash memory and free RAM as an extra layer of performance-boosting cache for your PC. Use up to four inexpensive flash devices to speed up your system. Add more speed to your PC without any hardware upgrade!Note:U will download trial version which can be used for: 4-hours for trial..

here is the downloadable link of eBoostr from rapidshare:

Download