If your machine is already infected, and you're asking questions like this, it sounds like it's already too late for good preventive action as
MustISO recommends.
Considering the time it takes to remove infections from a machine, and that you may never be certain you get all of it to keep it from returning, the surest and sometimes fastest way to know you're rid of a virus is to format the drive and re-install Windows from the ground up.
If you have critical files you need to save, start by removing the drive from your machine, booting another a well protected, fully backed up machine (active, current anti-virus, anti-spyware and firewall) to safe mode, and connecting your drive to it as a slave. You can use an adapter
like this one to connect any SATA or full size or notebook PATA drive to a USB port.
In the future, in addition to
MustISO's recommendations, BACK UP YOUR DATA. You can always re-install your OS as long as you have the installation programs for your software and backups of your files.