Surprised you haven't managed to get it to it work? I have win 7 64 bit, router, steam version and it works (although I have to start steam as administrator to see pings). Didn't think your setup was anything special? Have you tried taking machine to work and just quickly running it from there to see if it is your router/internet connection?
that's a logical fallacy, those games might use different ports, different protocols, and have different network characteristics, it could be triggering a faulty anti-DOS rule in a crappy router, it could be triggering a faulty NAT special-case rule, it could expose a flaw in your network driver, there's a million and one things that can go wrong on a home computer that only reveal themselves for certain programs, which aren't that program's faultor it could be an EA issue, yes. Just saying you can't assume that.