have you set ips manualy on the network or using DHCP?
Acrocosm is on to something, here...
When I first started getting into wireless networking (about 4 years ago) I used to get pissed as hell at my router. My compy and router would both say that I'm getting a perfect wireless signal but I could not connect to the Internet. What I had to do was go into my router settings via url entry (192.168.1.1 is default) and change around the IP numbers. Take a look:
Alrighty, this is your basic Network Setup Settings screen. Keep in mind that I have a Linksys WRT54G, so I have no idea where this would be found under your router's settings.
After you type in
192.168.1.1 into your browser's Address Bar, you may be prompted for a user name and password. The default is usually:
User Name: (Leave It Blank), Password: admin. After putting this in, your router's settings should come up. Look around until you reach a menu that resembles something like the one above.
Your
Local IP Address is the IP Address of your wireless router. This is the Address that your Compy/Wireless Card will use to send a signal to and from the wireless router. Most people leave it at the default (192.168.1.1, remember you used it earlier to access the router settings?) but as you can tell from the screen above, you
can change the address if you wish.
Your
Starting IP Address is the IP Address your internet service will start up with. As far as I understand, this
CANNOT be the same as your
Local IP Address. This is what caused me many problems and left me in the same situation that you are in, many times. I usually just changed the last number in the
Starting IP Address to one number higher than the
Local IP Address (in my case, the new number is 2). Remember to have the
DCHP Server ENABLED
In my case, I connect via PPPOE (User Name and Password given by your ISP), so if your ISP provides with this information, you maybe want to double check to see if you entered it correctly under the router settings.
Now you can just save the changes and give it another go. Not sure if this'll solve your problem, but it's worth a try.
[If anything, connect your compy to the router directly, via an ethernet cord (hardwired) and change around the settings if you can't get in wirelessly.]