First you will have to make sure that each computer can connect to an Ad-Hoc wireless network.
Host Computer
1. Turn on the host computer.
2. Log in using an Administrator account.
3. Right-click on “Network Neighborhood” and select “Properties“.
4. Right-click the broadband card to share and click on “Properties” and select the “Advanced” tab.
5. Check the checkbox next to “Allow other network users to connect through this computer’s Internet connection” under “Internet Connection Sharing“. The drop down box will allow you to specify the network connection that will link the host and client, wifi for instance. You should probably uncheck the “Allow other network users to control or disable the shared Internet connection“. If you want to limit the protocols shared, click on “Settings“.
6. Click “OK”
7. You will see the following:
“When Internet Connection Sharing is enabled, your LAN adapter will be set to use IP address 192.168.0.1. Your computer may lose connectivity with other computers on your network. If these other computers have static IP addresses, it is a good idea to set them to obtain their IP addresses automatically. Are you sure you want to
enable Internet Connection Sharing?”
Click “Yes”
Client Computer
1. Turn on the client computer.
2. Log in using an Administrator account.
3. Right-click on “Network Neighborhood” and select “Properties“.
4. Right-click “Local Area Connection“.
5. Click on “Properties“.
6. On the “General” tab under “This Connection uses the following items“, select “Internet Protocol (TCP/IP)“.
7. Click on “Properties“.
8. In the “Internet Protocol (TCP/IP)” Properties box, select the “Obtain an IP address automatically” option.
9. Click “OK” and Click “OK” again in the “Local Area Connection Properties” box.
Remember This
Each computer must have a unique IP address. If you manually assign IP Addresses and accidentally use the same IP for two computers, one of the computers will not work. It’s recommended that you set the “client” computer to obtain IP addresses automatically to prevent this from happening.
http://support.microsoft.com/kb/306126