Start by backing up your stuff, just in case. Ripping out malware is not an inherently risk-free activity, so you either have to live with the malware or commit to some removal risks.
If it were me, I'd make an AntiVir Rescue CD and an F-Secure Rescue CD, boot the system from each of them, and scan it. Give the system a wired connection to the Internet so it can fetch fresh virus definitions.
Once that's done, boot into Windows and scan the system with Superantispyware and Malwarebytes.
Next, install Secunia's
Personal Software Inspector, run a scan with it, and fix the vulnerabilities so this doesn't all happen again.
You can get AntiVir's Rescue CD in either .ISO format or in an .EXE that burns the CD directly:
http://www.avira.com/en/support/support_downloads.html
F-Secure's Rescue CD is in .ISO format, burn it to CD with burner software: download from
here