Ok heres what to do:
First, go to your internet settings (from the control panel, or open IE and select Tools -> internet options)
On the first tab, delete all cookies, files, and clear history. This does not actually get rid of anything, but will make ad-aware scan faster.
On the second tab, security, set everything to the default level and remove anything from trusted sites that you did not put there yourself -- normall this should be empty.
On the next tab, privacy, make sure its set to default.
Then, on the final tab, Advanced, hit "Restore Defaults"
What this does is makes Ad-Aware scan faster and makes sure IE has relativley safe privacy settings.
Next, download Ad-Aware and Spybot. Install them, and UPDATE THE DATS.
Shut down your computer and boot into safe mode (hit F8 after the bios screen but before the windows screen).
First, run spybot. Be sure to use the immunize feature as well. Next, run Ad-Aware. Do a "Full System Scan."
Then reboot your computer, and download and install all windows updates. If your computer is pre-SP2 you will probably need to visit the windows update site two or three times (a reboot before each time) to get all the updates.
Next, download and install firefox as a precautionary measure