Longtime mac user but new to wireless on the mac. We have a Belkin Pre-N router and my wife's "new" ibook (Airport, Panther) connected right off the bat.
But she can't connect anywhere that access to the internet requires a log-in. For example, we stay at a hotel where wireless access is available and you login using your room number. This happens simply by opening the browser and typically there is a redirect to the hotel server which presents the log-in screen. This is the same way T-mobile works, as well as many free networks.

OK, so we see the hotel network, and see it has great signal strength. Airport setup utility reports we're connected. The Network pref shows an IP address. But we just don't see the login window. If I enter the hotel server URL, I get "Can't connect to server". Same for Safari or IE. My work-issued PC using WinXP and IE goes straight to the server with no problem. The same thing happened at the library which has a free network that requires a log-in.

One weird thing. I was in Help for Airport Setup Utility and typed in "IP Address" and the hotel login window showed up in the Help Viewer window! I logged in and then Safari was able to connect! But after that one time, Help Viewer stubbornly remained a help utility and didn't magically morph into a browser. Any ideas?