The HDD should work. Just make sure you match the interface with the motherboard. If the cable connecting the HDD to the motherboard is a wide ribbon, it's an IDE or PATA drive, in which case you need to get a board with at least 1 PATA port. If the cable is just a normal SATA cable, you don't have to worry about anything.
Something to point out is that unless you bought the XP disc yourself (i.e. NOT the disk Dell sent you), you cannot use the current OS on any system besides the Dell. The disc vendors send you with prebuilt systems is a recovery disc that you cannot install with. The verision of Windows they use is an OEM version that ties itself to that specific motherboard and cannot be used in a different build.