You can get a very good virus scan and clean online, for free at:

http://housecall.trendmicro.com/

I've used it and it found a virus AVG SOHO missed.

There are a number of AV programs that can be run from outside of windows.
These will require the latest virus definitions so you will need access to a
working system that is online so you can download the definitions to be
saved to floppy, CD or USB stick.  Essentially you create the bootable
floppy or CD that contains the AV program and boot off it. Next you will be
asked to point to the location of the latest definitions. Then you will be
able to scan your computer's hard drive(s). Check here
http://www.freebyte.com/antivirus/#scanners

Many online scanners won't launch when infected by certain viruses as the
virus is coded to refuse access to these scanners. If you add the network
card and have internet connection you can have good success with a version
of Bart's PE (a bootable CD that runs a stripped down version of XP) that
has an antivirus plug-in. The easiest way to use it is found here
http://www.ubcd4win.com/ You need to have internet connection so that the
Anti Vir plugin can download the latest definitions. This CD is also very
handy in that it also has Ad-Aware to do a virus scan and you can also burn
files to CD/DVD with it so you can backup important data.

Download David Lipman's MULTI-AV tool to a uncompromised computer,
update it, then burn it to a CD and take it to the compromised computer
and let it run in safe mode.

If there is anything that can be cleaned it will do the job.