Make sure the drives are set to run as master and slave (there are jumpers on the drive to configure this) and then install the second hard drive (frm the fried computer). This will be the slave drive. When Windows boots up, find the drive in My COmputer, right click and select format. All data from this drive will be removed along with the viruses.
Is that what you wanted?
By the way if this is a Dell (you didn't say) then both drives must be jumpered as CS (cable select) and the main drive must be plugged in furthest from the motherboard.