Problem with airport

I'm fairly new to macs but when I go to airport and connect to the same linksys port I've been on for months, as of today it tells me I have full signal and doesn't tell me I'm not connected, but it won't load Any site I try, or msn, anything to do with the internet.

I've tried to diagnose it a bunch of times, and it says i'm not connected, but the bars in the top are still full.

When I connect with my roommates ethernet cable everything works fine,
anyone have a clue whats going on?

Use Network Utility (in your Utilities folder) to ping a website. It sounds like your LAN isn't the problem, it's possibly the connection from your router to the modem or your modem to network. If you can actually ping a website with Network Utility though it's probably Safari that's the culprit.

I usually do the whole "Unplug everything for a few seconds" trick and my wireless connection usually resets without further issue.