So, as a conclusion to this thread and the other I started here about my drives never spinning down... yesterday I did the swap. I put my MkIIa board and display in the MkII case and visa versa. Why you ask? Because I hate the feel of the MkIIa metal, and because it is slightly larger than the MkII case and won't fit in my car sled because the side tabs can't be bent out due to being blocked by mounting brackets. It also works out nicely that I can now use my smoke buttons (thanks Paul!!).

Result: Awesome. I now have about 7GB free on my 80GB and the drives spin down just fine! I must've had a bad RAM chip on the MkII after all, or I guess 4 more MB really does make a difference. I still plan on adding the fan controller and fan, and probably more RAM once it's usable by the player.

Here's some disassembly porn: