TV,
Maybe it's me but it's a tad difficult to work out how you've got the network configured (personally I like to see people drawing pictures with boxes & lines). I'm assuming here that:
(1) The desktop PC is connected to the ISP via the NetComm router
(2) The destop has a second connection (Ethernet?) to the Netgear router which your laptop is also connected to. (It's the two routers that's confusing me)
I suggest you might want to take a look at:
http://www.pcstats.com/articleview.cfm?articleID=1429 which covers sharing the internet connection in several ways (and includes those idiot diagrams I like)
If that doesn't help, confirm the connections please
batninth