The number of "in production" W2K servers would probably astound most people. I actually think this is a big issue and one that I find slightly concerning. As for blocking 139/445, since this is in the TCP Stack, that alone won't do very much for you.

What worries me even more is that on initial release of the advisory Windows XP was listed as not being affected in it's "default configuration", it wasn't until a couple of days later that Microsoft finally admitted that XP was affected, and that they weren't releasing a patch for it either.