Some Proform treadmills seem to be ok while others are also problem prone. I would guess anything made 15 years ago was made before they started to cut a lot of the corners they now do. If the treadmill is a very recent purchase, you might want call up the company and ask about purchasing an extended warranty. Even if you bought a model that has a problem repair history, it doesn't mean that your treadmill will be a lemon. Proform is priced to appeal to a large number of people and they sell thousands of units. The percentage of machines with problems may very well be quite low, but the numbers may seem high overall because they sell so many. If *all* of their machines were lemons, then they could not remain in business!
Here's a site with quite a few reviews on both treadmills and ellipticals:
http://www.treadmillsensei.com/
I found his reviews were mostly in line with other sites and he has reviewed more machines than any one other site. If you stick to your budget, or if you decide to splurge a bit more on your elliptical, it'll help you sort out which one sounds best for you.
Bambifox - it sounds like you've got a very nice set up! I wish I had that kind of space, but I live downtown in a city where space is rare

Here's to everyone's new found desire to get into decent shape so we can enjoy our old age!
BP