Basic wireless keyboards and mice usually work fine. If you get a keyboard with extra keys or a mouse with extra buttons, it will take some work to get them working. It's only the extra keys that won't work initially though-normal keys and two mouse buttons should work right away. There's lots of instructions on this site about it, but if you're new to linux it might take you a while to get extra keys and buttons working.
I recently bought a Logitech MX700 wireless optical mouse that can also be purchased in a set with a keyboard. I use Mandrake 9.2 and the mouse wheel worked right away. The back and forward buttons take a little work, but the eighth button doesn't work at all with normal mandrake 9.2.