While is some cases an older house might be better built, I'd have to agree with Jay. Regardless of how well built it was, things get old, roofs need replacing, window seals go, foundations crack etc etc.
I'd much rather a newer house of good build quality. Not to mention you get the advantages of newer and in most cases better build material technology and more up to date building codes.
In a newer house you're getting better window surrounds, better insulation, better wiring standards (ie. no aluminum wire, GFI's around sinks, breakers vs fuses), Higher efficiency furnaces and air conditioners, and just the plain fact that in a newer house you've got a pretty good chance nothing is gonna wear out with age any time soon.
Plus, 20+ years ago, just like today, there were plenty of builders doing crappy work, just as there are plenty doing great work. So I wouldn't use age of a house to judge if it's "better" or not.
Edit: Haha, Jay you beat me to it.