Ok, go into the router's control panel.
192.168.1.1
Select the "Wireless" tab and then go to "Basic Wireless Settings"
Check out the figure in the "Wireless Channel" box (it's probably stil on the default, which is channel 8 or 9 right?)
Change it to whichever channel is furthest away from the default (on mine the default was 8 and the channels range from 1 - 13 so the furthest from that was channel 1).
Click "Save Settings" and then "Continue".
Now, turn the PC
off. Turn the router
off.
Turn the router back on and wait for the lights to settle on the front, turn the PC back on - wait for the HDD activity light to settle and then log back in.
Hopefully your connection should connect automatically, if it doesn't you may need to start it manually. If you can't get connected at all you will need to attach a PC via a wire to your router and try again.
You might find that the first channel you try doesn't make a lot of difference, experiment with some of the others until you find one that works.
Please let us know how you get on