Trouble connecting to games with new router.

[Hello_Moto]

Recently switched over from a Dlink G604T to a Belkin N wireless modem router. Trouble is that i now have a lot of problems when attempting to join games - the "Failed to connect" message box pops up 80% of the time.

Here's my previous setup:-

router: Dlink G604T
DMZ: enabled
H/W NAT & firewall: enabled
S/W firewall: enabled (program exceptions added to Windows firewall & Zonealarm)

Here's my current setup:-

router: Belkin N wireless modem router
DMZ: disabled
TCP/UDP Port forwarding: enabled
H/W NAT & firewall: enabled
S/W firewall: enabled (program exceptions added to Windows firewall & Zonealarm)

As you may have noticed, i decided to port forward in my current setup as opposed to placing my IP in the DMZ. Could this be the cause of the problem....i keep reading about a lot of issues regarding DoW and NAT. The DoW Network test passed me with a good result apart from indicating "NAT detected". Putting my IP in the Belkin's DMZ is not really an option at present because it causes my router to lock up for reasons unknown :(

Any help/solutions would be appreciated.