Do you have another computer you can use to download some stuff and non infected thumb drive?
If so go to CNET and download the following as well as their update definitions where applicable:
CCleaner
Malwarebytes
Spybot Search and Destroy
Hijack This
Avast
I've also seen a lot of people talk about bitdefender but I've never used it but if this other stuff doesn't work then maybe try that.
So download all those onto the thumbdrive
Restart the infected computer in Safe Mode (without networking)
Install the programs and update their definitions using the definition files (where applicable). Some of these programs may give you a hard time installing/updating properly in safe mode but I forget which ones so if you encounter one just move onto the next program and try the ones that didn't work in regular mode after you've scanned with everything else.
You want to use these fresh downloads because even if you already have these programs on your system they may have been corrupted by the virus so you may have to remove the original installs.
Open CCleaner and run the CCleaner following the included instructions.
Run a full scan with Avast using the updated virus definitions (I think this one gave me a hard time updating with the definition file, if so just scan without the update for now. It'll still check for a bunch of stuff).
Then run Spybot Search and Destroy (full scan) following the instructions
Then Malwarebytes
Unless it is a particularly stubborn virus these programs should be able to deal with it. If not you can go back to CCleaner and see if you can remove it manually. Same thing with HiJackThis.
HiJackThis gives you a little description of each entry which is helpful but sometimes confusing. Usually any major problems should be apparent but you may want to take the report it generates and post it the HiJackThis forums and those dudes will help you figure out what needs to go. Do NOT remove things on a guess because you can screw up your system.
Then do it all over again in regular mode.
All of that will usually take care of even the nastiest viruses. If not unfortunately you may have to use your recovery disc. Hope you've backed everything up.
Good luck.