I actually run Windows XP under Parallels, and I have an plain, ordinary Windows keyboard attached to my MacBook. (Ie, I have no special application keys, no power/sleep/etc. buttons -- just the basic keys, two windows keys, and a context menu key).
Aside from certain key remappings you can choose to do from Parallels's preferences windows, the keyboard basically works in the guest Windows system exactly as it would in a real one. Print screen is print screen, not F13, and so on. Bring Windows to full screen and you might not even realize you're on a Mac.
The only exception, and there is presently no workaround that I am aware of, is that Parallels maps the right Windows key to the context menu key (the "right click key") and the context key itself gets mapped to nothing.
I say there's no workaround because unless Parallels has some option I'm not aware of, there's nothing that can be done about that particular annoyance. Parallels doesn't send any keyboard input whatsoever to the guest OS for the context menu key, so you can't just remap it in Windows.
