I have a month old iMac that I have in my dorm at school. It had no problem connecting to my school's wireless network up until a week or so ago. I am able to connect to my school's open wireless network, but unable to get an IP address. Basically, I have tried everything possible to get it to work. This includes reinstalling OS X, replacing the Airport Extreme wireless card (thankfully Apple paid for this), making sure wi-fi is the default connection method on the computer, and everything else you can think of. There is no MAC address filtering set up that I know of, and no one else has any problems getting on the Internet, even other Apple users. I know my computer's MAC address isn't blocked, because I changed it and was still unable to get an IP.

After doing some reading on the web, it seems as though my problem is due to a DHCP conflict with another computer.
Airport connectivity issue [Archive] - Mac Forums

Essentially, the network at my school is extremely overloaded, and it wouldn't surprise me at all if all the DHCP addresses were taken.

For the networking experts here, what is your take on the issue? If it looks like this is DHCP issue, I will go to my school's network admin and talk to him. But before I do that, I want to be sure I'm right.