vista share internet (vista ics with a 3g data card and wifi)
Start -> Control Panel -> Network and Internet -> Network and Sharing Center "Manage network connections"
Right click on the connection (that is connected to the internet, e.g. 3g data card) and choose "properties".
Choose the Sharing tab and check the box, "Allow other network users to connect through..."
If your computer is hosting some services you can choose Advanced and allow local area computers to access those services...
The ICS will automatically set your LAN (other network) connections to ip address 192.168.0.1 and will auto-assign any computers that want to connect into the 192.168.0.2-254 range.
Next, set up an ad hoc computer to computer network
Start -> Connect To "Set up a connection or network"
Choose "Set up an ad hoc (computer to computer) network" click Next You can choose a level of security (you may want to test it first without a password)