When Microsoft released their remote keyboard for Media Center, I was excited. Here was a wireless keyboard, including mouse and MCE-specific functionality. As an added benefit, it uses the Media Center IR receiver so you don't have to connect another one. It seemed to be exactly what I was looking for. I bought one early but was very disappointed. While I like the eraser-style mouse on a laptop (it's a shame they are disappearing), this one didn't work right. It was very difficult to control. It seemed that I could only get it to move a short distance with each push and it was really hard to center on anything. Despite my wife's request that I return it, I kept it just for the keyboard part. Now, I'm glad that I did. I finally figured out the secret of using the mouse.
There are two things I found make it a pretty decent mouse. First, you need to turn down the pointer speed a lot. This can be done via the Control Panel. This allows for better control and centering. Without it, I overshot the buttons a lot. Second, you have to have the keyboard aimed directly at the IR device. Anything in between, and it responds terribly. With a remote or with the keyboard keys, you don't notice because you are usually only sending one command but with the mouse, you are sending a stream of commands. This seems to make a huge difference. With a good line of sight, and slow pointer speed, it's pretty useful. I can even navigate the small buttons found on regular windows applications.
The one thing I still can't figure out is how to get the keyboard to work with my motherboard's BIOS. I have USB keyboards turned on but no luck. If anyone has this problem solved, let me know.