If you haven't yet heard about them, look for an original IBM PS2 Keyboard. These are were made for less than ten years beginning about 1986 but are of bulletproof construction and the benchmark for key responsiveness and feedback.
The one I'm using now was originally supplied in 1987 (when they cost about $225).
Obviously can only be found secondhand -- mine was from a flea market for about $5 and was a pretty unhygenic looking. But as you can see from the link they are easy to clean and come up like new (and have a slightly obsessive following) oh and if your computer is new you'll probably need a PS2 to USB converter:
I just bought the same set, and the keyboard is amazing in its feel. The mouse isn't bad either. But apparently there's a lot of problems with the connectivity on any sort of Microsoft keyboard.
I've had mine for a week or so and I'm starting to see problems with the mouse and keyboard dropping signals. I don't have any other wireless devices in the room, and the receiver is plugged into my monitor inches from my mouse and keyboard. This is common apparently, and I guess its only going to get worse.
I've got 30 days to return them for a refund, but I've never felt a nicer keyboard.
If anyone else has suggestions on a nice ergonomic wireless keyboard that would be super.