There’s a KB article that pretty much covers it: http://support.microsoft.com/default.aspx/kb/898060/ . For my money, a really good KB article, with detailed symptoms that allow you to quickly diagnose the problem from a network capture.
MS05-019 was re-released this month, and the update contains fixes for the problems listed in the KB. If you installed the original release of MS05-019 on any computer, it’s a Really Good Idea to upgrade that to the new version as soon as you can.
And if nothing else, if you’re having a weird connectivity problem, just check WindowsUpdate isn’t offering the newer version to you.
Windows Server 2003 SP1 wasn’t affected by the vulnerability, but is affected by the issues documented in the KB article above; if you’re affected (easy to tell from a network capture), give PSS a call to obtain the hotfix.