I also have a MS-Wireless desktop.
It works fine, except I'm using it via the PS/2 ports.
Also, it clogs up my syslog file with Unknown keycode errors.
Well, try it on the PS/2 port if you can.
I'm trying to find a script or something that will set all of the keycodes for me.
I've been trying to dwindle them down by using setkeycodes.