Airport connected but can't go online, using Snow Leopard on a new Macbook Pro 2.66

HELP!!
I am new to Macs and just bought a Macbook Pro 2.66 GHz, I have been using Airport to go on internet in my house for the last 3 days and no problem, but when i tried using it this evening I can't get on the internet. I have full bars on airport, in Network it says Airport is connected and has an IP address but everytime I try Firefox it says "Server Not Found" and in Safari it says "You Are Not Connected To The Internet". I have tried a direct cable Ethernet from the router and that works n I can go online....I'm now very confused and very tired (it's after 4 in the morning!) and i've been searching online on another laptop that is able to connect via wireless to the same router.

It is a Telsey router CPA-ZWTE42TUK (think thats it!)

Its WEP Password

TCP/IP- Using DHCP (I have renewed the DHCP Lease)

Firewall - Allow all incoming connections

If anyone has any solutions they'd be greatly appreciated, also I'm new to posting threads so before I figured out how to make my own thread I posted this on another one!

I really hope someone can help this damsel in distress

Thank you!

go into sharing in your pref pane, make sure you have internet sharing on with
correct prefs;D