Cameron, any particular reason you want a dual 1.25GHz MDD instead of a late model 2003 single 1.25GHz MDD as your parts machine? Persumably you'd be keeping it for its power supply and such and not its CPU card.

BTW, this might be interesting:

http://cgi.ebay.com/New-APPLE-G4-Xserve-1-33-GHz-Dual-CPU-661-2834-/350411091454?pt=CPUs&hash=item519620edfe

No heat sink though, as far as I can tell.

They're not as fast as a 1.8 GHz, but they should have the 2MB L3 cache...