You can try putting the old HD with XP in the new PC. If the chipsets on old and new motherboard are from the same company (VIA or nVidia or SIS), it MIGHT work, but chances are less than 20%.
A restore CD is useless, it only works for the PC it came with.
Check the XP-CD-key on your current installation and compare with the CD-Key on the side of the PC or on the sticker on your PC-manuals (or COA).
If different (and it probably is), you could borrow someone's real XP-CD (must be same Home or Pro as your old PC), and install/activate with that key.