We use this for our Intro to Networking class
Network+ Study Guide Deluxe Edition
If you buy it just make sure you buy new or that used one comes with the 2 CD's. They are gold! The first CD includes the full text of the book, flash cards, a test engine with all chapter tests, and the second CD has a virtual lab. The virtual lab is wicked, you piece together network components just like you would have to in the real world, but its all on the CD. It has an XP envrionment, 2003 server envrionment, linux and mac environment. I find it extremely useful to learn, because reading text and passing tests is one thing. Getting a job and physically setting up a network is another.
I'd post a screenshot but I'd probably get in trouble for legal issues.