As it is, I bought the complete motherboard/CPU/heatsink/RAM package from a guy who had the MDD June 2003 1x 1.25 Ghz machine. Basically he's parted his machine and I'm getting its core, so there shouldn't be any conflicts at all. Just a cleaning check and maybe some new thermal paste. Otherwise GTG.

And if for some reason I want to return my machine to stock, I simply put the original mobo/CPU/RAM etc. back into it.