I'm sorry no one seems to be helping you. Lets see what I can think of.
Do you still have your CD you used to install your OS? Is it windows XP or do you have a copy of windows XP (service pack 2?) Then head to www.ubcd4win.com (on another computer) download the program and create an UBCD (Ultimate Boot CD) It has all sorts of useful tools, but mainly it has several antivirus and antispyware apps. Before you create the disk, though, click "plugins" and scroll down the list. Update all the antivirus and antispyware apps by clicking "config". It may take a while, but it will be worth it.
Once you create the CD (or create an ISO image that you then burn to a CD), return to the infected computer, check your CMOS settings to ensure that your computer will try to boot from CD before your hard drive, then boot from the CD. Select the option at the top of the menu, the rest isn't important now but can be handy. Run as many scans as you can (all of them?) overnight or sometime like that, and see if that doesn't find your culprit. (I'm surprised that NOD32 didn't find it....)
There's some other utilities you can try on the UBCD, honestly, I haven't had the time to try them all- there's lots! See if theres something that will help you.
If that doesn't work, there's a windows explorer like application you find at the bottom of the screen. Try to get rid of the Google toolbar this way. You can click that, and then move any important data over onto external media. Try to save as little as possible so you don't take the virus with the data. (This is always good practice, even if you're not planning to reformat).
You can reboot the computer, boot off the CD again, and enter the windows recovery console (near the bottom of the initial menu) if that suits you better.
Finally, as a last resort, you can reboot, boot off the CD again, and in the initial menu that pops up, you can select "Derek's Boot and Nuke" or something along those lines. It's the third or fourth one on the list. It will completely reformat your hard drive. Then you can install your OS again. Drastic measures, but perhaps necessary?
Save that for last! Unless you don't have anything important to lose, then it will definitely solve your problem. :)
Get back to us on this!
--The Comodore