Hi Vista & Windows 7 are virtually the same thing when it comes to this. That`s why Vista drivers
usually, there`s always one, work properly on 7 if you can`t find a Windows 7 driver
Step 4 in the link mentions the Bluetooth modem. It does say turn off encryption on the BB then have the laptop find the phone first, set the laptop part up then setup the BB.
Found this on RIM`s website about setting up the Bluetooth modem. KB12544-Connect a computer to the Internet using a BlackBerry smartphone as a Bluetooth IP Modem
If none of that helps then maybe someone on this bb forum can help General 8300 Series Discussion - Curve - Page 2 - BlackBerry Forums Support Community
Hope this helps you get this sorted out as I`m out of ideas, I`m sorry to say. The only consolation is that using the USB cable is quicker if you can`t get this working.