I read through this entire forum trying different settings and configs, but none seemed to work. After a whole lot of 714 errors and some 734 errors I was able to get things working using this procedure:

(Stolen and re-edited from an earlier post)

Step 1 - Connect Your BlackBerry 7100g
Make sure your BlackBerry is connected by USB cable, and your BlackBerry Handheld Manager is running (just launch BlackBerry Desktop to run it.) This is necessary for using the BlackBerry as an external modem. You cannot use BlackBerry as a modem unless you have BlackBerry Handheld Manager running in the background!

Step 2- Verify Modem is Functioning Properly
Go to Control Panel -> Phone & Modem Options. In the Modems tab, you should see a new Standard Modem (it will not say BlackBerry so do not get confused) on a new port (such as COM3, COM6, COM7, etc.). Click Properties -> Diagnostics -> Query Modem. You should see the following on Windows 2000 (below, “OK” will be replaced with, “Success” on XP if you want to get real technical):
ATQ0V1E0 - OK
AT+GMM - BlackBerry IPmodem
AT+FCLASS=? - OK
AT#CLS=? - OK
AT+GCI? - OK
AT+GCI=? - OK
ATI1 - Research In Motion / BlackBerry IPmodem
ATI2 - Research In Motion / BlackBerry IPmodem
ATI3 - Research In Motion / BlackBerry IPmodem
ATI4 - Research In Motion / BlackBerry IPmodem
ATI5 - Research In Motion / BlackBerry IPmodem
ATI6 - Research In Motion / BlackBerry IPmodem
ATI7 - Research In Motion / BlackBerry IPmodem

Step3 - IMPORTANT SPECIAL CONFIGURATION STEP
Click Properties -> Advanced and add the following extra initialization commands with the appropriate carrier-specific APN Setting (remember I’m an AT&T account on Cingular and therefore am using the AT&T setting):

AT+CGDCONT=1,"IP","proxy"

Step 4 - Add a New Internet Connection (some things are a little different on 2000 vs XP but pretty similar so try to follow what I have put here)
2000 - Close the Phone and Modem Options and the Control Panel. Create a new connection with Start -> Connect To -> Show all connections -> Create a new connection; or
XP - Close the Phone and Modem Options and the Control Panel. Create a new connection with Start -> Settings -> Network Connections -> New Connection Wizard.
1. Click Next
2. Select "Connect To The Internet" then Next
3. Select "Set up my connection manually" then Next
4. Select "Connect using a dial-up modem" then Next.
5. Check only the Standard Modem (if prompted).
6. Give the connection a name such as "BlackBerry Modem", then Next.
7. On the next screen, pick one of the following phone numbers, depending on your AT&T/Cingular phone enter phone number *99***1#
8. Click Next.
9. On the next screen,

Username:
Password: CINGULAR1

I DID NOT DO THE FOLLOWING STEP. (IN FACT I REMOVED THIS ENTRY THAT WAS PREVIOUSLY THERE DURING TESTING. LEAVE BLANK TO START AND CHANGE IF YOU CANNOT CONNECT BY NAME.

Step 5 – Configure DNS for Cingular
1. Go to Start->Settings -> Network Connections
2. Right-click your BlackBerry Internet icon, select Properties.
3. A window will open. Click the Networking tab.
4. Click TCP/IP Settings and then Click the Properties Button
5. Select "Use the following DNS server addresses:"
6. Enter Preferred DNS server: 66.209.10.201; and Alternate DNS server: 66.209.10.202


After following all of these procedures I starting getting 734 Errors. I knew I was on the right track as without the proper config I was getting 714 Errors. The only way I was able to clear the 734 was to turn off the BB completely (yikes! first time I had to do that!). After the reboot and Cingular GPRS network sync the notebook was able to connect without errors.

Connecting this way is certainly slow, but definitely usable. I hope this helps. This is a great forum and there are many knowledgeable people here that I was able to piece this together from. Thanks everyone, for all your help, and keep up the good work! (Anyone know when the Edge enabled RIM drivers will be available for the 7100gs?)
Cheers!
-speed