I have an older than dirt Kensington USB Bluetooth dongle that is actually a rebranded / relabeled MSI Bluetooth dongle. Due to the way WIDCOMM originally did licensing and firmware, it is easier getting an organ from the organ donation list than it is to get updated drivers and firmware for most Bluetooth devices.
For whatever reason that I haven't looked into yet, the dongle isn't automatically discovered correctly like most newer BT dongles with the default XP SP2/Vista BT support.
In an effort to get something working under Vista, I ended up pointing Vista to my original XP inf directory for initial BT support of the actual dongle to get rid of the 'Unknown device'. To avoid 30 or 40 'unsigned driver' warnings, I edited the local group policy to 'ignore' the fact that the drivers might be unsigned. Sure, not best practice, but I don't mind bending the rules on my home desktop machine. If I break it, I'm the one that has to fix it anyway.
I ran the WIDCOMM setup in XP SP2 compatibility mode and it installed everything correctly as far as I can tell. There are a few sections of the programs that have quirky display problems, but I just wanted some base functionality with this old dongle until I decide to get a newer USB 2.0 Class 1 Bluetooth dongle.
At least I don't have to suffer with the Toshiba Bluetooth stack that installs 40 COM devices on initial install, even if you are only going to use one COM port. A lot of programs still don't handle anything above COM8 correctly.
An unpatched Toshiba BT stack is also easy to crash if you have your system discoverable and in range of someone with exploit code. Sure, not very common in the real world, but given how difficult it is to get updated Bluetooth stacks from vendors, I am sure most people are still running the older versions.
I am hoping Broadcom, who bought WIDCOMM, will do something like what Agere did with their software modems. They released a 'generic' driver for their chips that might not have all the features of the original OEM drivers, but you can at least download and get basic functionality if you lose your original CDs.