[ManchestrMorgue]

Spybot S&D
Adaware
Windows Defender

seem to be the three popular free ones. It doesn't hurt to install all three and run them all. It's not like antivirus software, where you should only have one installed.

Also, could download Kaspersky antivirus and install the 1 month free trial. This also detects malware, trojans, etc. and may be helpful.

After you have cleared this, do as ___V___ said and use Firefox instead if IE (if you aren't already). It will stop a lot of infections just by using it instead of IE.

Make sure you have an anti-virus installed - AVG or Avast are reasonable free alternatives.

At the end of the day, when you have a lot of spyware on your comp, it can be really hard to get it completely clean. If you have your original Windows disc and applications discs, sometimes it is quicker just to back up all your data (photos, docs, music,email, etc) and reformat/reinstall. That way, you have a fresh system that you know is completely clean. However, if you don't have the discs for everything, this doesn't work.