You really need to decide what you have done in the past, what you want to do, and where do you want to be in 1-3 years on a bike.
If it's just Family riding, a Trek 7000 for the two of you "MIGHT" be enough. The 2007 model is $289 and the new 2008's are priced at $309. My wife rides a 7000 WSD (Women's Specific Design) and is very happy with it. It is stable, shifts well, and is built well and should last us a long time.
All Manufacturers have an entry level bike that will do you well. Stick to your guns and to your budget. Keep the bikes in good order and clean and if you need to trade up in a year or two, sell them on your local Craiglist.
Chris
P.S. I work for a Trek/Fisher/Bianchi Dealer. I try to remain neutral when it comes to my recommendations on Bicycles. I do believe that an entry level LBS Bike is a better value than a K-Mart or Walmart Bike.