I don't have an 8100 but I do have an 8830. I was having similar problems as some of the folks here. My bluetooth would find the BB but didn't provide any DUN services, etc. Only headset.
I think it's very dependent on what Bluetooth drivers are provided with your Bluetooth adapter (built-in or otherwise.) I found a website with instructions that (after a great deal of effort) worked for me.
Click Here
The part that gave me the biggest headache is that I had to completely remove the software (not just uninstall the drivers) for my Thinkpad. I did that through the old-fashioned "add/remove programs" (named slightly differently in Vista.)
But, in the end, this worked very well for me. It just took some patience and persistence. I think MS's stock BT drivers for Vista are just seriously lacking.
Hope this helps.