Windows 7 - Can't connect laptop to new router

I have a Netgear DGNB2100 Wireless N router. It is connected to an old PC via Ethernet cable. That connection works.
While downloading a 64 bit driver to use for the USB adapter for my PC, I connected my laptop to the wireless network with the laptops WiFi card (Intel PRO/Wireless 3945ABG), and used the internet for about ten minutes.
I then configured the USB adapter for my PC, after disconnecting the laptop.
My laptop will detect the network, but when I put in the password, I get a message saying Network Security Key Mismatch, and am prompted to type the key in again.
I have also tried pressing the WPS button on the router instead of typing in the password with no luck.
The laptop is an Acer Aspire 5920, with the aforementioned Intel PRO/Wireless 3945ABG network card, and it is running Windows 7 Professional 32 bit.

It might help to go into the Netgear router configuration page and reset the password, use the same password so the laptop can still connect. Be sure and save the settings after you reset the password.

I had to do the same thing with my Dlink router last night because my wireless network kept disappearing.

It might also help to reset your IP by doing this.

You can can reset your IP address by :

1. Opening the Windows Command Prompt located in Start -> Accessories or
Start -> Run -> Type in either "cmd" or "cmd.exe" (without the quotes)
2. Type in "ipconfig /release" (without the quotes) 3. After releasing the IP, type in "ipconfig /renew" (without the quotes)

I tried resetting the password, that did nothing.
Which machine should I reset the IP on/ My Win 7 x64 PC using the Wireless USB adpater, the old XP PC using ethernet or my laptop?
Also, will I have to change any settings on the router config? At the minute, the router retrives the IP from my ISP (Orange)

Try is on the Win 7 machine first. Sounds like things went bad after you reconfigured the USB adaptor on your PC. Somehow that created a mismatch of your key. I would reset the Router and try again by unplugging it or hitting the reset button.

I have turned off the router at least twice, to no effect, I did think it might be an issue with my PC and the adapter, so I will try that next