Another very serious vulnerability in Windows NT/2k/XP/2k3 RPC services was announced yesterday, and it could enable another Blaster to hit the Internet if people don't patch their boxes soon. Translated: we will see another worm, because there are just enough people out there that don't know how to patch or won't be able to roll it out to all of their systems in time. :?
What I'm truly worried about is a "cross-vector" worm -- one that spreads BOTH via vulnerabilities and email. This way, it can get past the firewall to the internal network as long as someone executes it. I expect it to exist one day, and that will truly will shake up people's consciousness about security. I hope. Anyway, make sure you hit Windows Update, use a virus scanner, and have a firewall and you should be all set.