Aquiring Network Address with Wireless

hi, i am trying to get wireless to my dads machine downstairs so he can do his ebaying with out hasseling me all the time. I have set up the wireless network to be secure and they kind of connect. when the computer finds the network it has excelent signal but it allways stays on "aquiring network address" and when you look in the status for the ip address it says "Invalid IP Address" and it is set to 0.0.0.0. it is like that on both machines. I am using AD-HOC because it is only two machines (will be three when i can be bothered to fix my little sisters machine) so i can't be bothered to spend money on a router just for two or three computers.
thanks.

after an hour and a half i thought i would try using static ip addresses and somehow it worked. i think it is because it is because with wireless it thinks that there is a router in the middle but with my network it is just one computer connecting to another one.

half an hour later and a restart from virus scan update and it is messed up again like before. does any one know how to fix this and make it last. thanks.

sorry. five mins later and i try the app that was on the driver disc and it is working again.