As regards introductory astronomy texts, I'm in agreement with Margaret
Mazzolini and am a proponent of Kaufmann & Comins' DISCOVERING THE UNIVERSE, 4th
edition, published by W. H. Freeman. I've used the book successfully here at
UCSB, and colleagues of mine at the community colleges report that the book is
at just the right level for their students as well. The text puts a lot of
emphasis on student misconceptions, which I think are very important, and does
so in a way that doesn't insult the intelligence of the students. The book is
also inexpensive (it's a softcover) and the enclosed CD-ROM is very valuable. I
recommend it highly.