If you format the drive, it should You can also a system restore.
Start>Programs>Accessories>System Tools- What this does is back the computer up to a certain time on the computer. I've used it a few times. If the virus is bad enough though it may not be enough and you might have to format the c drive which will restore it back to factory, but you may not have some programs that came with your computer when you bought it. That's why it is good to have recovery disks because they have all the necessary programs that your computer originally had when you bought it.