1) Will Harpoon Classic run on Windows XP Media Center?
From other folks using HC97 v1.54, no, it will not run on XP. I have no personal experience with this claim. Harpoon Classic 2002, HC Gold, and the latest, HC Commanders Edition, will run on XP with no problem. It certainly runs on mine.
2) Is it truly the original Harpoon, but with the bugs largely fixed?
Harpoon Classic Commanders Edition (the latest iteration) stays true to the original Harpoon Classic model. The keyboard commands, layout, and other stuff are going to be very, very close to what you saw in the original version.
However, it has
LOTS of great new features. i.e. The Prowlers now do area jamming, great new maps, the Western Pacific theatre is now included, Land Units can Move!, etc..... And many, many bugs have been stamped out.
3) Is Harpoon III a better improvement over II, than II was over the original?
I don't like to compare if Harpoon II was better or not versus Harpoon Classic. Both communities have their followers and their enthusiasts. They share common history, but they are pretty different in their implementation.
I will say that Harpoon III is
MAJOR improvement over Harpoon II. Like night and day the number of bugs fixed, running speed, databases, etc.
I hope that this counts as three "Yes" answers. Love to have you join back into the community.