probably 2003
there is no ET demo
However, due to problems with the single-player aspect, the multiplayer portion was released on May 29, 2003 as a freeware standalone game
as far as i remember, some voice commands were different (axis were HORRIBLE)
and the mp40 sound was different, aside from that, its was pretty much like etmain 1.0
What I remember is that the et MP test wasn't supposed to be released at first, but it was distributed to press/media for publicity. Some (Belgian) company then Sold the MP test for a couple of euros to its members/suscribers. Other sites also gave it away some days before they then 'officially' released it.
there is no ET demo
However, due to problems with the single-player aspect, the multiplayer portion was released on May 29, 2003 as a freeware standalone game
http://www.fileplanet.com/122724/120000/fileinfo/Wolfenstein:-Enemy-Territory-Multiplayer-Test
and the mp40 sound was different, aside from that, its was pretty much like etmain 1.0
(but i may have forgot something)