I had a similar problem with a Mini USB Bluetooth dongle from IOGear I picked up today. Device contains a standard Broadcom chip, and windows 7 could install drivers for it, but it would ask for drivers for every device, and wasn't able to actually use any of them.
The drivers shipped with the device included the full widcomm bluetooth package, which it seems most manufacturers provide. [Manufacturer's Drivers for Vista/Win7 32/64]
Downloaded the Bluetooth Driver installer from Broadcom's website, had to use google cache, website seemed to be down. Broadcom Download, and [Google Cache].
It's a small download, it downloads another installer to actually do the work. But now that it's installed, the native windows 7 bluetooth support for my stereo headphones (A2DP device) and cellphone (calls/audio) are working great.