Okay, so I have figured out that I can use AT&T's 3G phone network for internet, for free because my phone (Samsung A707) has an unlimited data plan.

Now, when we're in the car on a road trip, I'd like to share this internet with my friends.

I've developed this idea:
1) Create an ad hoc network, make sure all the computers are connected and can ping each other.
2) Connect the 3G phone to the 'host' computer via bluetooth.
3) Dial out to the network, enabling internet access on the 'host' computer.
4) Share the dial up connection over your wi-fi adapter in Windows Vista's Network Connection Settings.
5) Internet should be working on all the laptops! Right?
Wrong.
It apparently isn't working.
What am I doing wrong guys? Every time I've tried to share an internet connection like this, its worked, but it doesn't work with the cellphone.

Any ideas?


EDIT:
I've been at this for 3 days now, and finally have internet through one 3G phone split between 2 laptops running Windows Vista Ultimate.

Here's what I did.

1) Determine your 'host' computer. (Whatever laptop is going to interface with the phone...)
2) DISCONNECT from any wireless networks you're currently connected to. Make sure the IP of your wireless adapter is set to "Automatic" for now.
3) Enable Internet Connection Sharing on the 3G phone connection.
(In Windows Vista's Internet Connection Settings. Right click connection > Properties > Sharing > Check the box that says "Allow users to share this computer's internet connection" and then select Wireless Network Connection for "Home network connection". Make sure to check what services are allowed by clicking "Settings". Check that Web Server (HTTP) is enabled at least.)
4) Connect to the internet on the 'host' computer via the 3G phone.
5) Create an ad hoc network, and connect all your computers.
6) On every computer, change the network type in the "Network and Sharing Center" to a "Private Network" instead of the default "Public Network". If you get it working right, you should be able to ping the host computer and the host ping the others. Note, you may have to F*** with the ad hoc network to get it to do this, just what ever you do, DO NOT CHANGE THE IP ON THE HOST MACHINE!
7) You should now be able to use the internet on all the computers in the network.

Troubleshooting:
1) Delete ad hoc network profile on ALL the computers
2) Disable Internet Connection Sharing on the 3G phone connection
3) Restart all the computers.
4) Follow steps again. (This sounds dumb, but it fixes stuff... oddly enough).