From what I've read of svchost, it can be called upon to run several services and you can find these using task manager (ctrl-alt-del). You can also look at performance and a slow PC often means something is occupying too many cpu cycles. You can try shutting off processes one at a time and rechecking the performance tab to see what what drops your cpu usage. If you find a specific service that, when stopped, causes a significant drop in cpu usage, you might investigate to see what that service is used for and how necessary it is. Check here


http://www.blackviper.com/WinXP/servicecfg.htm

Your options could be to either set it to manual if it runs automatically or disable it if it seems of no use. You can always re-enable it if you find some function not working. Good luck.