You will need to reinstall all drivers and the old drivers can give problems when replacing them with new one.
And I don't know if there is something Compaq related (special master boot record, or whatever) on the disk which may give problems on your new system. But when I placed a 2 GB drive from my old Compaq 486 to my Pentium 75 networkserver it would run perfect after changing some drivers, but this was Windows95.
My case has so many fans that it hovers above the ground
.