Have you looked at these bikes in person? It's very important to look at the bike in person and "try it on" so to speak. You always want to ride the bike before buying. There's nothing worse than getting the wrong sized bike and being stuck with it.
Have you looked at the Trek 3900 D? There seems to be a lot of bang for your buck. I'm mainly looking at it coming with disc brakes. They cost extra, but I have found them to be worth every cent.
http://www.trekbikes.com/int/en/bike...ries/3900disc/
I ride a Trek 4300 D. It's very similar to the 3900 but comes with a little better derailleurs and better fork. Mine was close to $600.00. This time of year, you may be able to find a deal at an LBS (local bike shop) on 2010 models.