Whatever you do, don't get the Microsoft Natural Ergonomic Desktop 7000 wireless keyboard/mouse combo. They're both basically useless ime, the wireless connection drops out for a second every couple of minutes. This will tilt the hell out of you.

I love the physical properties ie shape, weight, general feel of both the mouse and keyboard though, if you can find wired versions (I used to have the natural ergonomic keyboard 4000 which is the same keyboard but wired - then I spilled a glass of pepsi in it) def try them out.