ok, then do that. as long as the connections are the same (ie. sata - sata, ata - ata) you will need to re licince it, so make sure you have the key before you remove it from your old pc.
So plug it in, there isnt anything complicated about adding a new drive to a machine. However do not expect the old install of Windows to work, and if it did, to be valid (read; legal).