Swami should not be posting under an OSX topic.

DustinS/mikevickrocks - airport card in his iMac, and a Linksys BEFW11S4 Router (Version 3)
Well the airport card won't make any difference unless you're actually connecting via airport. Are you? Yes Airport has an internal NAT firewall. So does the Linksys. You will need to log into the Linksys & enable UPnP on it. That will hopefully make the firewall go away. If you're using Airport, I posted instructions on how to deal with it. See the UPnP section here Connection problems? Check here first! (click on link)

swami: Make sure your XP firewall is disabled! Also check this about Norton FW: (a) Configuring Norton Internet Security, & also (b) Reconfiguring Norton Firewall

Also check your modem/router type & make sure UPnP is enabled. Likewise see the UPnP section in the link I gave above.