you on exC&W/NTL cable?
use 194.168.4.100 for primary DNS and 194.168.8.100 for secondary DNS.
these are the official DNS your router should be getting given from VM, so you can also use them in the manual DNS section of windows networking too.
from what you say here ,id not be trusting anything these so called techs are telling you, were did they get this 'DNS server to 4.4.2.2 and 4.4.4.1 respectively ' from, its NOTHING like anything Virgin Media use and so only valid IP pinging would work as you cant resolve any URL to the right IP without a working DNS or failing that,the currect entrys in your OS configs .
for instance if your DNS are set wrong the command
ping www.ntlworld.com
would not work, but
ping 212.250.162.12
would work if your IP and routing were set right.
so you are saying you have followed my advice above and set the USB ethernet to 192.168.2.2, the routers IP is 192.168.2.1 ,and your 'subnet mask' is set for 255.255.255.0
[edit]
if for any reason the manual 192.168.2.2 didnt work and some machine reported an error of some kind ,change the 192.168.2.2 to another No at the end that doesnt clash withthe other PCs on the LAN, try 192.168.2.22 as the router might be giving out the *.2 already and so clash and thats not good.
you have checked the routers web pages from a working wired PC on the LAN for the 192.168.2.2 and its showing up on the page so the USB pc IS connected to the router?.
you still cant ping and web browse ?
forget all this windows configure and reinstalling belkin software other than the devices wireless driver, its just complicating the matter, all we need to know after you manually set the right IP on the USB wireless ethernet, is can the router see the 192.168.2.2 as connected, and can you ping/browse the above URL/IP after making the changes to the wireless USB PC now?