Microsoft is pulling the Xbox Live plug on both the original Xbox and original Xbox games as of April 15th this very year.
The announcement came courtesy of Major Nelson, who explained it on his blog
"I wanted to let you know that on April 15, 2010 Microsoft will discontinue Xbox LIVE service for original Xbox consoles and games, including Xbox 1 games playable on Xbox 360.
"Our first step in this process will be to turn off auto-renewals for those members who only use Xbox LIVE on a v1 Xbox."
But why, Major, why?! (Aside from the possibility that only three people in the world use Live with an original Xbox now). WHY!
"While I can’t comment on the specifics, this change will allow us to continue evolving the LIVE service with new features and experiences that fully harness the power of Xbox 360 and the Xbox LIVE community. We did not make this decision lightly, but after careful consideration and review we realize that this decision will allow us unprecedented flexibility for future features."
The removal of this kind of backward-compatibility was further explained by Xbox Live general manager, Marc Whitten
"Your Xbox LIVE community has grown to 23 million strong. And as we look down the road, we’ll continue to evolve the service with features and experiences that harness the full power of Xbox 360. To reach our aspiration, we need to make changes to the service that are incompatible with our original Xbox v1 games. We will contact the Xbox LIVE members directly impacted by this change and if this includes you, I encourage you to check your LIVE messages and associated e-mail account over the coming weeks for more details and opportunities. We view you as a partner in this process."
Okay, we say "explained", what we mean is 'waffled a bit'. Either way, Xbox support is going on April 15th - you're a partner in it. Live with it.