Thanks!
And at the same time you were posting that, I found SharpKeys and got it set up how I wanted. Ok, I just played with KeyTweak and does basically the same thing: a GUI around the low level registry entry that the Windows keyboard driver reads. They're both exactly what I want.
In case anybody else wants to do this, here's my remapping (put this into a .reg file, save it, and import with RegEdit). It does the follow:
Caps Lock --> Control (I do this on all my Windows machines, for emacs and frankly anything else)
Bottom Row: remaps so that Macbook Pro works as:
Fn, Control, Windows, Alt, Space, Windows, ContextMenu
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout]
"Scancode Map"=hex:00,00,00,00,00,00,00,00,05,00,00,00,1d,00,3a,00,5b,e0,38,00,\
38,00,5b,e0,5d,e0,38,e0,00,00,00,00
What would now make this perfect is to find some new keys for the MBP so that the legends were correct: a 1-unit Windows key and a 1.25-unit Alt key. But for the squirelly MBP keyboard.