there are tons of XP services that you can disable to keep them from eating up resources and making the computer a little slower, also a lot of startup programs that you can disable too.
I didn't bother creating a 2nd windows XP user, I just disabled everything I don't need. To me it seems like a pain to have a 2nd windows account, plus I don't need these services for normal computing so I have 1 account optimized.
Go to start - run - type in "services.msc" > hit enter > look at all of your services, look up each one at http://www.theeldergeek.com/services_guide.htm
and double click & disable services you do not need.
Also, of course, hit start, msconfig and go to startup, and research everything on your startup here http://www.greatis.com/appdata/atyouroption.htm
and turn crap off on startup that you don't need.
you can download the windows XP tweak guide and do tons of little crap like that to make your pc a little faster.
Let me know if you notice an improvement.