Am I the only one here who uses Avast! antivirus? I find it a pretty good AV package (better than AVG actually) and is ultra light on resources. Plus, the Home Edition is free, and supports Windows XP x64 Edition. It also comes with Script Blocking, Internet Mail Shield, Web Shield, IM Shield, Network Shield, P2P Shield. Adequate protection.
I used to use it until I got infected, it did not stop the Trojan from performing its nasty piece of work on my PC so I got rid of it, not everything that is free, does not always work, you get what you pay for, Mate.
I like Kernel for windows data recovery software which is very meaningful while you lost your important data from your hard drive. It can easily recovers the accidentally deleted files or folders, corrupted files and data etc. You can try it from - http://www.windowsdatarecovery.com