Wireless internet help :(

[Vince]

Ok, so I'm back at home again. Now, my family has wiped the harddrive clean and installed Windows XP, so it's clean. We're trying to put it on the network using their 2wire wireless internet card, but we're having problems. The computer shows a connection, and is sending packets somewhere, but when I try to start up IE or in any way use the internet, the program I use shows no connection to the internet. Any ideas how to make this work? I've seen the same problem on my girlfriend's laptop, but that works kind of randomly...I'd really like to get the computer on the internet for while I'm home (I HATE using my mom's iBook for the internet ), though I AM quite worried that my family will just mess up the computer again.