I wouldn't touch DataObjects with a 10-foot pole. It's an odd little proprietary thing without much of a user base. You should evaluate NHibernate and Entity Framework 4 to see which suits you best; you'll be able to get help with either of those on StackOverflow.

If you've got some money to spend, I recommend looking at LLBLGen to make your life easier.

Ah, thanks for the warning. I've already seen plenty of NHibernate posts on Stack Overflow, I can see how that is going to be a useful resource. Thanks for the help- I'll recommend we pick up LLBLGen. One of the reasons I was looking outside of NHibernate was the idea of the XML configuration files. A GUI will go a long way to avoiding that problem...

EDIT: Just seen Fluent NHibernate, too. Interesting.