I recommend http://www.avast.com/en-us/index for realtime antivirus, for after you clean your computer.
I would check for rootkits with http://www.gmer.net/.
Then check for malware with http://www.emsisoft....n/software/eek/ and http://www.surfright.nl/en/hitmanpro/
Use CCleaner to clean remaining files and registry entries. http://www.piriform....ccleaner/builds
Use Microsoft fixit to repair windows. http://support.microsoft.com/fixit/
Also nuke the suspicious folders inside these folders (if you are unsure about one, search up on it):
C:\Program Files (x86)