start>settings>control panel> selelc system applet
now in system properties dialog box.
select system restore tab
in this tab of system restore
check on turn off system restore.
I just asked the same question, and I found the answer.
Check Microsoft Knowledge Base article 310405 on how to do
it. It's easy. Go to Start-My Computer-Properties-System
Restore tab, and their is a box to check/uncheck.