I had some issues getting the ArduinoBT connected.
I think there are some issues with the XP USB drivers. Also, in my case I had used 2 different bluetooth dongles at different times and one used the windows driver the other installed some other drivers.
In the end I went through and deleted all the com that were related to USB. Then I searched and found the Arduino-BT and paired to it successfully.
I selected the BT board in the IDE (I was using v0010, but I understand v0011 has some BT improvements) and set the baud rate.
It took a little time for me to get the time between pressing the reset button and clicking the download button on the IDE before it worked - and it did give an odd error message when it didn't work - but it has been working ok since.
I hope this helps a little.
Regards,
Mike