Your post caught my interest, and I may have found some information for you. Most of the information I gathered from [url=http://teambeyond.net/forum/index.php?/topic/2218-halo-2-vista-comprehensive-installation-guide-by-roosterru/]this Halo 2 Vista installation guide[/url]. Just to inform you, I've never played Halo 2 PC, so I don't know if this will specifically help, but it may. Apparently soon after the game released, a crack (cheat) was discovered to bypass the cd key issue. There is a patch (a .dll file) that corrects the issue, but various forum posts I came across seem to describe a similar issue that you seem to be having. That patch may help. To answer your second question, the fate of the Halo 2 PC multiplayer servers seems up in the air. There were various reports of them being taken down and coming back again, but the latest I've seen is that they were due to stay up until the end of July 2014. This is, however, unconfirmed, so I don't entirely know.