When you say Virgin Broadband, I assume it is their ADSL service via the phone line and *NOT* Cable broadband via a Cable Modem or TV Set-top box?
The DG834G is a combined "Router & ADSL Modem" suitable only for ADSL via the phone line.
Virgin's *SUPPORT* pages appear to be worse than useless and I couldn't find anything that actually detailed the settings for an ADSL router.
Go into the router's configuration pages by typing its IP address of 192.168.0.1 into your web browser. You will be prompted to enter a Username & Password, the defaults for which should be on a label on the underside of the router. You will need to enter your Virgin account "Username" and "Password" into the settings. Check also that these settings are correct:
Encapsulation: PPP over ATM (PPPoA)
Multiplexing Method: VC-Based
Virtual Circuit: VPI=0 VCI=38
Modulation: Multi mode
See how you get on with that.