I have a Vision Fitness treadmill and it works very well for me but it is one of the upper end models, T9600
. I bought it when I was actually doing lots of running so the extra expense was wise as I find many home treadmills just don't cut it for true training.
I also agree with michaeld, Precor makes a very cushy board system and there are some days I wish I went that route.
I have tried ellipticalls and still prefer a treadmill. I get a better workout while running and using a treadmill is more beneficial to actual training for runs, running sports, etc., IMO, as you are ACTUALLY running and using the same muscles, well almost, nothing beats going outside for a run.