Your Vista firewall settings will have reverted to default then. Which model SpeedStream do you have? Are we supposed to guess? Almost all high speed routers have internal NAT firewalls. Question is whether they support UPnP or not or whether their UPnP is enabled or whether their UPnP support is efficient enough.
Also check your control panels & program folder to see if there's a trend firewall or any other software firewall.