computer running slow

"OK some basic troubleshooting

Did you add any hardware or software at the time when your comp started going slow ?did you uninstall anything?

what did you set your virtual memory to?

and post those answers here http://delltalk.us.dell.com/supportforums/board?board.id=sw_winxp"

the only thing i remember is that my computer started to run slow after the newest service pack was installed.  So i tried to do a rollback, but my computer said that it couldnt do that. 
my friends tried to set my virtual memory, but it wouldnt set.  for example, we would set it to a certain value, but when we restarted the computer, it would go back to it's intial setting.
and it's just not my computer that is running slow, the load time is WICKED slow!  it takes maybe 3 times as long as it did from before.

what's happening?

thanks for your time

~mike