I'm very excited that I'll be getting a working Vista USB Bluetooth adapter. My roommate actually purchased it and it does work with Vista, unlike my Motorola Bluetooth adapter. An added bonus is that the driver is actually Windows Vista certified so none of those scary driver dialogue boxes that ask for you to continue.
I purchased it from newegg. It actually wasn't that expensive. I already have it set up on my computer (I used my roommates to try it out and it worked great). The specific adapter was the TRENDnet TBW-105UB USB 2.0 Compact Bluetooth Adapter.
The specific reason I wanted a Bluetooth adapter was to use my Stereo Motorola Bluetooth Headset. It is great for listening to music, plus, since it has a built in microphone I can voice chat with it too!