Just wanted to throw my 2 cents in... look at NHibernate also. There's a steep learning curve, but once you get familiar with it you won't look back.

Hello, Mike! Agreed. The reason I didn't mention nHibernate is that it cannot offer the prolific papers, presentations, blogs and other organized supports available whenever MS releases something new. Also, I'm sure you'll agree that the nHibernate documentation with version mismatches etc may be dismaying for a first-timer still grappling with NET concepts. Get past that and IMHO it has a huge amount to offer- not least being already past certain issues/mistakes that MS has just implemented, with predictable consequences that were experienced and resolved in nHibernate years ago.