I've been pretty happy with my wireless mouse. Its a microsoft intellemouse explorer. I use it for game play quite often, and havent experienced any problems. You do need to get used to the "feel" as it is a little heavier, one advantage this mouse has, is it uses standard AA batteries, so I just use rechargeables, and keep a spare set handy.
I havent tried a wireless keyboard yet, but I plan to when I do my next build (end of this week, if all goes well)