I am having the same problem. I am using the WRT54G. It is connected to my desktop and I used the CD to install. When I try to connect wirelessly, it keeps saying "Acquiring Network Address". After about 2 minutes my laptop informs me that I have "Limited or no connectivity."
I have done diagnostics on my laptop and there are no problems. My network key is entered correctly. Also, a friend also has the same problem when he tries to connect to my wireless network.