If the drive is PATA, hook it up to an IDE channel as Master or Slave by setting the jumpers correctly on the drive. Just make sure the channel in the BIOS is set to Auto, to detect the drive.
You wont need to reinstall Windows if you're just adding a drive to an existing rig - you do need to make sure the boot order has the existing drive with the OS set to boot first.
If the drive is an SATA drive, all you need to do is hook it up to a SATA channel and then make sure the boot order is set correctly.
Once you ge this done, go to Disk Management (Control Panel->Administrative Tools-> Computer Management ->Disk Management if you want to format/partition it.