Protect Your PC - Dos and Don'ts - Part 1
DO run weekly antivirus and anti-spyware scans,this cannot be emphasized enough.
Windows XP - Dos and Don'ts - Part 2
DON'T be afraid to reinstall Windows. It's not hard, especially if you install onto a blank hard drive instead of wiping your existing drive.
Windows XP Dos and Don'ts - Part 3
DO keep your software !including Windows) patched and up to date.
Windows XP Dos and Don'ts - Part 4
DON'T compress the contents of your hard drive to save space. Compression slows down your whole machine. Just buy a new drive.