Common Windows Solutions:
Windows XP Service Pack 2
  (download from Microsoft)
Features:  Protects from harmful internet attachments, improved privacy control, reduce pop-ups,   firewall protection and security center, spam protection, crash protection, better wireless support.
Grisoft Anti-Virus Software
  Free Version   -  Licensed Version
Excellent support for eliminating or reducing virus attacks.  Supports email attachments as well.  Highly recommended product.
Spyware - Adware removal
detects and removes 99% of all Spyware and Adware products from your PC.  A must for everybody who surfs the internet.