Assuming you have Virgin's Cable broadband, I presume you now have a Hub (which is a Modem/Router) and your old "Cable/DSL Router" which previously connected to the Cable Modem?
If that's correct, I'd suggest you connect the old D-Link's WAN port to one of the new Hub's LAN ports and continue to connect all computers to the D-Link. Don't disable its DHCP server. However, I believe that both Netgear and D-Link operate in the 192.168.0.0 Subnet, with the routers having the address 192.168.0.1 and allocating addresses between 192.168.0.2 and 192.168.0.254. You will therefore need to change the address of your D-Link router from 192.168.0.1 to something like 192.168.1.1 or 192.168.2.1 to avoid a conflict with the main router. You're probably safer making the change in your D-Link than in the new Hub.