Da Bears have been horrid in the first round, other than Urlacher, Grossman (who the jury is still out on), and Tommie Harris (who is also too early to call) they haven't gotten one impact player, and they've had some high picks. However, from the second round on they've gotten as many good players as anyone:
1991: Chris Zorich in round 2 (a multi-year starter and a great guy to boot)
1992: Jeremy Lincolon in round 3 (who wasn't great but was a starting CB for a playoff team at one point)
1994: Jim Flanigan in round 3, Raymont Harris (who was better than Salaam although he had a short career) in round 4
1995: Todd Saurbrun in round 2, who is now the best punter in the league (although not with the Bears
1996: Bobby Engram in round 2, Chris Villariel in round 5
1997: Marcus Robinson in round 4
Not that impressive so far I'll admit. From here it gets good though:
1998: Olin Kreutz in round 3
1999: Rex Tucker and Marty Booker in round 3, Warrick Holdman and Rosevelt Colvin in round 4, and Jerry Azumah in round 5
2000: Mike Brown in round 2
2001: Anthony Thomas in round 2 (laugh all you want, but he was the ROY and was pretty much the entire offense for a division-winning team that year)
2002: Alex Brown in round 4
2003: Charles Tillman in round 2, Lance Briggs in round 4
2004: The late rounders from this draft obviously haven't gotten to play much yet, however, Bernard Berrian (rnd 3) and Nathan Vasher (4) have at least shown potential.
I'm not saying they're one of the better drafting teams, obviously they would be doing better lately if they were, especially considering that there first round picks from 1990 to 2002 were Mark Carrier, Stan Thomas, Alonzo Spellman, Curtis Conway, John Thierry, Salaam, Walt Harris, Enis, McNown, Urlacher, David Terrell, and Marc Colombo (What? You haven't heard of all of those guys?), but I do think finding that many impact players later in the draft separates them from Arizona, Cleveland, etc.
I think their general poor performance over the last decade or so is more due to injuries and poor coaching (especially on offense) then their drafts, although all those first-round busts haven't helped.
Oh, and sorry for going on so long.