I recently used the Updater application to update to Sumatra 1.7, but now it won't launch at work where they still have Windows 2000. (My work organization is a bit slow, but they're getting there, finally.)
I checked the main page of Sumatra Portable for O/s compatibility. As of 2011-08-12 @ 0759EST, it listed Windows 2000 as being compatible. I then checked the forums and support pages here and didn't find anything. So I checked the Sumatra Download page, it doesn't list Windows 2000 as one of the O/s for Sumatra 1.7.
If this post is in the wrong place I apologize.
I've updated the page to remove Windows 2000. Likely it was dropped in 1.6 or 1.7 without any mention in the changelogs and so few people use it that no one noticed.
Sometimes, the impossible can become possible, if you're awesome!