highly recommend cc cleaner. it is excellent for removing temp internet files etc.
www.ccleaner.com
if you think you are having problems with spyware i reommend malwarebytes.
www.malwarebytes.org/mbam.php
both of these are free programs and i often use them in computer clean ups with excellent results.
matty
January 2010
CC Cleaner is my favourite freeware.
T
January 2010
You don't mean the outside I presume...
AVG is well respected as an Anti Virus and is free
Piriform's Ccleaner (free) is useful for clearing regular rubbish in temporary files
Spybot Search & Destroy (free) is useful for clearing out Malware
There are others - people tend to recommend only what they use themself
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix desktop pcs.