Anti-virus
http://free.avg.com

Spyware
If you would like to scan your system for spyware, here is a regiment of software to use.

Start with this one, superantispyware portable
http://www.superantispyware.com/portablescanner.html

Run combofix
http://www.bleepingcomputer.com/combofix/how-to-use-combofix

Run malwarebytes
http://www.malwarebytes.org/

Run spybot search and destroy
http://www.safer-networking.org/en/mirrors/index.html

Run ccleaner
http://www.filehippo.com/download_ccleaner

Backup Software

Mozy — 2GB Free Online Backup
MozyPro