Do you really mean re-install from scratch or repairing by re-running the setup from the CD?
If you are repairing the existing, then the virus is already present and the rest follows.
Download for free, click here and run this and see what you find.
There are addresses out there which will scan and preumably deal with an infection for free. That may be the best route to start with, Others on this forum will doubtless offer addresses.