I go wireless.My PS3 is a 20gb so I use internet connection sharing with my laptop.I used to be abel to get NAT 2 through ics but now my firewall doesnt give me that option.I have linksys wrt150n router,too,it causes some problems.Even with linksys router and ics Im able to connect to other just fine.Try opening these ports on your router.
PORTS:
TCP: 80, 443, 5223
UDP: 3478, 3479, 3658