In addition to Kaspersky, I highly encourage the use of
Crud Cleaner (freebie, but be sure to transfer those cookies you want to keep!)
http://www.ccleaner.com/
and B-C Wipe.. not free but a really good proggie for keeping everything uncluttered on those file slacks, swap files and free spaces.
http://www.jetico.com/download.htm
also for encryption of your "personal files" go with Kremlin.
http://www.kremlinencrypt.com/
(I have used these programs for many years..)
red