Reading and Xbox HDD on a PC

[BitStream]

I put a small temporary hard disk in my xbox to test an installation and once I had it sorted I removed it and installed a large replacement drive. I have tried reading the smaller hard disk on my PC but the PC won't boot with it attached? I tried another small hard disk and the same thing happens. The bios sees it and it's jumpered correctly. What's going on and can I use the disks again on the PC?