Okay, Got the computer shut down neatly. Poweroff, Dismantle, unhook drives, label them. Unhook PSU, unplug cards and stash in bags. Remove Mainboard and stash.
Start cleaning the case out from the dust, then insert new mainboard, screw it in (mistake, should have checked the CPU cooler first, needs additional fastenings there) .... and then I see. RAM. Unlike what I had thought it wouldn't fit. Meh, silly me. I really should have checked if the RAM I had would fit before ordering. Eff.
Now I had to find an old case and scavern the computer up into working, It does so, somewhat, right now. Great :/
Next goal, working on a Gentoo based small system for a Via C3 cpu, needs to fit in 128 Mb and I really dont fancy using ulibc and similar tools, so I guess it will take some hacking. My guess is that I need to setup a CHOST Chroot on the Dell machine first, and from that go on and build a targetted system for the C3 (it lacks the cmov instruction for one)