Go to start, control panel, add new hardware let it search and see if you can find it. If it is found let the internet install the appropriate drivers (you will need SP2).
If it can not be found go to control panel again, hit system, go to hardware tab, hit device manager and see if bluetooth radios, generic bluetooth radio + microsoft bluetooth emulator is there. If they are there try scan for hardware changes or update them if they are there by using right click on each. Hope this helps.