John Papas has an interesting article on the topic in the current issue of MSDN Magazine, Migrating from ADO to ADO.NET. His approach is pretty straight-forward - "Here's x in ADO, here's what it has become in ADO.NET, here are the differences/enhancements/etc" - which I think is helpful for someone who hasn't worked with ADO.NET much yet & is trying to get a handle on how the technologies map to each other.
If you are getting close to actually porting code, I'd recommend also reading Bill Vaughn's take on the subject, Migrating Code and Concepts from ADO "Classic" to ADO.NET. He comes at it from a more conceptual level - "What are your routines in ADO actually doing, and how can you get the same or better functionality in ADO.NET?" Between the two articles you should be able to get the conceptual underpinnings you'll need to get you started.