If you are going off of overall importance to this team you have to put Bourque up there just behind the "core" Trading for Bourque changed the course of this franchise forever. Yeah, he was only here a bit over a year.. but he turned a team that just as easily been broken up and scrapped for prospects into a Cup winner and IMO was a big reason that Blake, Sakic, and Roy all returned to the club following 2001. (if there had been no cup, who knows what would have happened, Blake would have been gone for sure... and I can't say for sure that Sakic and/or Roy would have been retained)
Granted, the Bourque era saw the Avs toss alot of prospects out the window too, but it was worth every minute of 2000-2001 .....
Lemieux also has to be given alot of credit for really getting the Avs-Wings rivalry into full gear... which lead to the teams Arms Race of the late 1990's and early 2000's...