Well, the best I can do is January of 2001. I looked in the SEIV archive for 2000 and Puke is in there, a lot. My guess would be he is the oldest and most consistant of the regular posters. Hadrian had a post early on about his website ( I guess some things never change
) so he would probably be in the running. And there are a few of the original beta testers, which Hadrian is one of. I am not sure how many of them still post though.
Geoschmo