Ad Aware is free
Note: Clear ALL your cookies, use Firefox or Google Browser or Safari to do most of your surfing, enable a firewall asap, set your cookie settings at advanced (only cookies going back to original site)
Look at Regedit to get rid of some of the startup items that you're stuck with... if anything says TROJAN change the name, that will stop it calling in or out, without deleting taking some of your files with it.
See these files:
Those are database files, if they are not making a call to a DB that is running from your PC delete or change the name.