I use Windows via Parallels a lot. I like to have the all the keys in windows mapped the same keys as the Mac (shift+2 should get me an @ sign etc.). When I set up my XP vm sometime ago I did find a Keyboard map that mostly worked and that was OK, but after hunting around I couldn't find it any more (or a different one that was decent and mapped all the keys I want to use), so I decided to make my own.
This actually turned out to be pretty easy using the The Microsoft Keyboard Layout Creator from within windows and Full Key Codes on the Mac.
The only slightly anoying thing is the hash key (#). In OS X alt+3 gets you there (on a UK Keyboard at least), in Windows I can't map the alt key so I have to use ctrl+alt+3. I can live with that.
I have also tested this layout with a USB Apple Keyboad and it works
99% (the = key on the numeric keypad is not mapped, I honestly don't think I have ever used it, so again, I will live with that...).
Anyway this works in XP and Vista for sure, I would expect it to work in Windows Server 2003 and 2008 also. Windows 2000? MS say it will, suck it and see I guess.
If you think you might find it useful help yourself...
MacBook Pro UK Keyboard layout for windows.zip (252.62 kb)