A google search does not seem alarming
"Default Block Microsoft Windows 2000 SMB" - Google Search
What Norton you run? 2009 version is the way to go if you stick with Norton.
Im asking because you mention Windows Defender. Dont know about old Norton but newer disables Windows Defender and they dont recommend you to enable it after wards. Make sense or just what they have to say, dont know. I know Avira suggest the same except they dont disable during install.
There is a problem with AV products without out much HIPS protection avoiding Defender. Does not take much effort to find some malware which they skip and Defender stops

Is far from useless.
Unless you actually downloaded and installed the "scanner" computer is not infected. Infection do not come from screwing up browser and making you turn off computer. Also how close you were depends on how Vista is set up with UAC, protected mode and what not. Firefox also dont make it that easy to run programs off the net. What site was trying to do by making it hard to get rid of. Use task manager next time, close IE/whatever browser process. The idiots exploits peoples panic and/or lack of knowledge.
If you want some supplement to Norton/Defender try Malwarebytes Anti-Malware
Malwarebytes.org Easy to update and dont conflict with anything and if you get infected it is very good at removing.