I have made a UK G4 Keyboard Layout for Windows, so that the keys are correctly mapped when using VirtualPC or VNC.
[robg adds: I haven't tested this one, (but I did download it to make sure it was at least what it claimed to be). However, I have heard occasional complaints on keyboard mapping in VirtualPC with non-US keyboards, so here's at least one possible solution...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040512103302676