Backdoor dvldr virus

[shadowdr]

Well pc cillin picked it up doin it's sunday noon scan with three files that were quarentined.I deleted the files and followed the advice on their webpage about uninstalling it's components through the regestry,only two folders so no big deal.I have a iinksys router with a four port switch and have the shareware version of zone alarm.
What i am wondering is how i got it and why didn't norton pick it up when it happend?Doesn't the router offer some protection from viruses?I dont think that the trojan ever actually connected to the address that it was trying to send to,but i cannot be sure as it uses rundll.32 to get out and it being a valid app it might have permission to access the net through zone alarm.I also deleted file and print sharing as per the website but am i safe now?What were they trying to get from my comp?Should i be worried that i have used a credit card online recently?
I also uninstalled norton as it would no longer run after the virus was detected by pc cillin.Is there anmything else i should do?
any thoughts would be appreciated.

[skab]

I was kinda curious about the firewall in a routerand just what effect it would have. Right now my networkall goes thru my main rig which has my anti virus (PC CILLIN) and I'm hoping thats supposed to be checking anything coming in even if it's going to one of the other computers. At least that was how I understood it in the first place. The problem is if it pigybacks in on a legit program then the firewall is useless! Do they make routers that or cable modems that have virus protection? That's what a guy needs but then you'ld only have to have one anti-virus program and firewall.

[shadowdr]

I should say that the pc cillin was not installed right away as i have just put this system together and tested the ram and oc'ing before installing many of the proggies i use and the newer zone alarm doesn't have give you the ability to see the programs it is letting access the net like the older one did.I assumed that being behind a router offered me more protection than it actually did and probably got it during testing.