I have to confirm that the 8700g works great with T-Mobile/Edge as a modem for my XP Pro installation. Just follow the instructions given above.
Now I have a question. The Edge speed supposed to be in the range of 300k or even 700K speed range if I remember correctly. However, the speed I am reading when connected to the Internet shows 115.2K. I think that this is a limitation of the softmodem that the BB Desktop software (4.1) installs. In
My Computer -> Manage -> Device Manager -> Ports
you will see the RIM Virtual serial ports have a throughput limitations set to 115200 bps. That corresponds to the Standard Modem (through USB) that uses one of the ports and also maxes out at 115.2K.
I am wondering if there is a trick to increase the modem speed so that the limitation will be set by the available bandwidth and not through the modem?