I still reccommend running chkdsk as HDD errors can happen even a week after reinstallation of windows. memtest86 I believe would be the best memory tester...
Go through [link=http://www.hardwareforums.com/windows-xp-security-guide-9738/]this thread[/link] and you will get lots of tools to protect your computer... Yup! and now they have an advanced version of it as well.... which is [link=http://www.memtest.org]memtest86+[/link].
