I just stole this from the Virgin Media site (What can I say, im lazy!)
To enable modem mode on your Super Hub
1. Make sure you are connected (wired or wirelessly) to your Super Hub (So just connect with your cable as normal)
2. Open your Internet browser.
3. Log in to your Super Hub's administration interface by entering 192.168.0.1 into the address bar (not the search bar) of your Internet browser. If you have changed the IP address of your Super Hub, you will need to enter its new address into the address bar instead.
4. Enter your Super Hub's administration username and password. The default details are printed on the back of their Super Hub. If you have changed the default username or password, enter those details instead.
5. Once you've logged in, click Advanced Settings at the bottom of the screen to access the Super Hub's Advanced Settings page.
6. Click Modem Mode on the left-hand menu. If you don't see the Modem Mode option, reboot your Super Hub by disconnecting and reconnecting its power supply, and the new firmware will be downloaded.
7. Click the Enable Modem Mode tick-box.
On the right of this page there are details explaining to how to connect your router to the Super Hub.
9. Click the Apply button. You'll see a confirmation box asking if you want to continue.
10. Click OK.
The Super Hub will reboot into Modem Mode. Once in Modem Mode, the options on the main administration interface are restricted and greyed out, including wireless options.
Note: Once in Modem Mode, the IP address you use to access your Super Hub changes from 192.168.0.1 to 192.168.100.1
You should now be able to connect the Modem to your old Netgear router and have it work like you were used to
*Edit* Also, if you run in to any issues or have anymore questions, the best thread to ask in would be
Virgin Media 50mb Thread
