I have just managed to overwrite the Sky firmware to that the proper Netgear firmware is installed on my DG834GT:
1) dowload the newest firmware from the followiing website:
Support Page
2) Dowload the recovery utility from:
Support Page
3) After you unzip the recovery utility make sure the latest firmware img file is in the same directory.
4) Turn your router off, hold the reset button IN, re-connect power until the two left-most symbols flash alternately.
5) Double-click UpgradeWizard.exe file on your computer. Click Next
6) A screen with "Adapter Card Lists" appears so choose the card that connects to the machine you are using and click Next
7)There should be one and only one item in the Device List. Click Next. (if it doesn't appear first time cancel and go back to (5) mine worked the second time) Click Next
8) Click Upgrade. Wait - it takes a while before the dotted line begins and a message tells you are successful.
9) Click Close to complete the recovery.
10) Turn the router off and after 10 secs restart.
11) Log-in at 192.168.0.1 with admin and sky (if not try password).
12) You now have to set up all the data supplied by your ISP.