Switching any dongle to the Microsoft stack
On desktop Windows with a Bluetooth USB dongle, it is nearly always possible to disable any third-party stack and replace it with the Microsoft stack. The Bluetooth standard includes a transport specification for USB connections (as well as serial and others) and 99% of all dongles support this USB standard and therefore all communicate with the Bluetooth software in the same way. (The one dongle I have seen that doesn't is a Bluetooth 3.0 dongle bought from Trust).
To change to the Microsoft stack all one generally needs to do is to switch the device driver handling the dongle, then the Microsoft stack will automatically start and use the dongle. In Device Manager select the adapter/device for the Bluetooth Radio (see e.g. in Stack Identification), select "Update Driver ...(...)(...)", then "Browse ...(...)(...)", "Let me pick ...(...)(...)" and choose "Generic Bluetooth Adapter" if offered. (Some dongles have drivers with different names, see the list in the second section in "%windir%\inf\bth.inf", e.g. "Belkin Bluetooth Adapter", "IBM Integrated Bluetooth". etc.) At that point the Microsoft Bluetooth stack should become active.
Uninstalling the previous stack
It may be preferrable in all cases however to actually uninstall the other stack software. I haven't seen any problems where Widcomm/Broadcom was present but issues do occur for other stacks. For instance BlueSoleil runs at start-up and grabs the Bluetooth dongle for itself even if the Microsoft stack was using it previously.
On machines with the Toshiba software, from Add/Remove programs you may need to remove the Bluetooth Stack for Windows by Toshiba. If so run the C:\TOSHIBA\MS_Bluetooth\BtMon2Inst.exe installer to install the BT monitor, and finally reboot the machine, whereupon the system will detect the radio and install the necessary Microsoft-supplied drivers as above.
The document Belkin F8T012 and Microsoft Stack downloadable from http://32feet.net/files/folders/1118/download.aspx describes how to install the Microsoft stack, and also includes the steps necessary to install a Bluetooth device that Windows wasn’t originally aware of.