I'm not for sure how PC's work exactly, but are you sure you have the drive installed as a master drive? If it's a slave configuration, it won't boot, or at least I assume it won't. Also, what kind of connection does it have? ATA, SCSI, IDE, or whatever. I've had problems sometimes with SCSI drives unwilling to boot. Of course I work Macs, so your mileage may differ.