Help with Keylogger removal

Hello all. I'm new here, and was hoping to find some sage-like advice on how to possibly search for and remove a keylogger program from my computer. I have a suspicion that a house guest installed a logger, but have no way to know for sure.

I run Windows Vista along with the following software tools:

McAfee Security Center (Free version with Comcast internet subscription)
SpyBot S&D
LavaSoft AdAware

I'm basically looking for a free software solution that will detect keyloggers specifically and remove them if possible.

I read a little bit about Spyware Doctor 5.5. I know I can get a free version of it through my Google account. Is it any good for Keylogger detection?

Since I feel convinced that it was installed by my house guest, I'm pretty sure the logger he used would be a freeware or commercial application.

Any help provided would be greatly appreciated.