Compaq hard drive won’t swap into Dell

I installed Windows 2000 Pro on a Compaq Deskpro. The Hard Drive is a Western Digital 6GB 7200 rpm in a removable bay. The client needs to take it home to do additional work.
When I install it on a Dell the computer will not recognize it. Is this aBios issue or related to the Compaq utilities written on the first 3 MB of the drive. Any suggessions?