This is a great tool for viruses and all sorts of malware (spyware, adware, etc). It is web based so you don't have to download or install anything. It can also detect vulnerabilities in your Microsoft applications and recomend the fixes. 

Launch HouseCall  

Cleanup!

This is a great little application that removes temporary files created while surfing the web, empties the Recycle Bin, deletes files from your temporary folders and more.

Download Cleanup!

Mozy Online Backup

This is a great way to protect your data online. And with the link below, they will give you 2GB for Free. Or you can sign up for their unlimited backup for $4.95.

Get Mozy

Click on this link, hit home useres, and sign up for free. They'll ask you for an email address and a passrword and send you a link to verify the email. You get a link in the email to download the software. You download it, install it and sign in with your user name and password.