Internlet connection sharing ...

Enabling on XP and connecting to from Vista using wireless connection:

First I established an ad-hoc wirelss network using Vista:

Network sharing centre Set up connection or network Setup wireless ad hoc
Give it name and I disabled security in this case.

Now you should be able to connect to this network from XP machine.

Now enable ICS on XP machine - right click Internet connection (not wireless) and select properties. Then in the Advanced tab tick share this connection. Think I also shared files etc. This gives the other connection - the wireless connection a static IP address 192.168.0.1. And this is the gateway (and DHCP server) for the other client machines (but this happen automcatically on the client machines)

That should be it - you can watch the connection in the Network Sharing Centre to see if you get Internet - and it'll prompt you for what sort of network this is.