I'm a Tolkien geek, that's how I got into message boards!
As far as reading the fabulous books, I too reccomend starting with the Hobbit....it's easy, fun.
Then do the Lord of the Rings trilogy. It's long, and intense.
If you are into knowing more after that, try the Sil....but it is in a different writing style, dry, rather like a history book....yet the stories it gives of the history of middle earth and all the peoples is incredible.
The atlas is a good idea if you are into that sort of thing!
The library is also a good idea....so you can get the hardbacks. While The Hobbit is a quick read.....The Fellowship of the Ring, The Two Towers, and The Return of the King are lengthy suckers, better to have the larger size of a hardback.
The Barrow-Downs is a good (geeky) Tolkien Forum.