Microwaves can cause problems with 2.4ghz devices as far as I know. The main combination to avoid is a wireless router at 2.4ghz and a 2.4ghz wireless video sender, the sort of thing that lets you play video from your pc to a tv in another room without cables. These two won't get on well.
I wouldn't expect it to be a problem with a wireless keyboard, though equally I would expect microsoft keyboards and mice to give problems under almost any circumstances. I'd be happy with a 2.4ghz logitech set, but will probably also use bluetooth when I get around to losing the cables