They still sell them, and recently went on sale. I also have one.
IMO it wasn't worth it. They are a novelty. They are produced by another company and sold by microsoft. The software ONLY work with IE, so if you use firefox or etc you're out of luck. I use it log into windows, but that's it. It's kind of handy. I'm not surprised it doesn't work with XP 64, they didn't appear to have much support for them last time I was at there website.