I figured I would post this considering that people may not know about this (and should be more than enough to keep your computer going strong)
Spybot - Search and Destroy - This is a
free Spyware / Adware protection program that is regularly updated and works extremely well.
Avast! Antivirus - This is a powerful Antivirus program that is free,
if you only use it for home desktop protection. Corporate or Business licenses are not free.