can't display the pages even if i'm connected to my router

so basically i just moved into this apt and there is a cable wireless router which my roomates use without problems. my computer connects to the wireless but when i open firefox or explorer it wont display the page. it says page cannot be found, like when you are not connected, but i am connected! so there must be something i need to change in my settings but i have no idea what!
can anyone help me?

Do your Browsers work outside of this "home network"? Was it working before you moved?

Can you PING a Website from a Elevated Command Prompt (assuming this is Vista) or from a Command Prompt (XP)

Try resetting the IP Stack:

1. To open a command prompt, click Start and then click Run. Copy and paste (or type) the following command in the Open box and then press ENTER:
cmd
2. At the command prompt, copy and paste (or type) the following command and then press ENTER:
netsh int ip reset c:\resetlog.txt
Note If you do not want to specify a directory path for the log file, use the following command:
netsh int ip reset resetlog.txt
3. Reboot the computer.