For those that never got past 2005....
Today at midnight Pacific time, Xbox Live 1.0 (original Xbox) was taken down for good. I was able to get on last night for a few final Halo 2 games, which I hadn't done in about 4 years.
Strangely about 2 hours ago I was able to still connect, but a few minutes ago I tried again and apparently it's finally down for good.