There are quite a few books on the market dealing with astronomical-equipment. There is however one book that experienced amateur astronomers often recommend to beginners to start off with, The Backyard Astronomer's Guide by Terence Dickinson and Alan Dyer, This book has some great chapters on astro-equipment.
There are many sites where you will find tutorials, tests and articles on astronomy equipment. I will name a few that I found very useful myself.
The Belmont Society for beginning and Intermediate Amateur Astronomers offers some great tutorials on telescopes, eyepieces and filters. Then there is Tod Gross' Weather and Astronomy site with lots of Astro-Product reviews. Another good site to visit is Ed Ting's Telescope Review Web Site with telescope and eyepiece reviews, but also with a beginner's advice. Then there is my favourite site that I can recommend to you, Cloudy Nights Telescope Reviews with test reports on telescopes, binoculars, eyepieces and filters, a special beginners equipment forum, major articles on observing, astronomy for kids etc. A great site. Also visit Dennis Bischop's Telescope Buyers FAQ, a must, not only for people who want to buy a telescope, but also for all beginning amateur astronomers. Here you will find answers to a lot of questions you might have concerning equipment, books, beginners' tips etc.!
There are two Yahoo groups you should join if you are interested in astro-equipment:
The first group is Talking Telescopes, a group devoted to the discussion of astronomical equipment, including telescopes, binoculars, eyepieces, books and star atlases, software, and more. If you have a question or comment about astronomical equipment? This is the place to visit. In the files section you will find articles, tests, links etc. Once you are a member of this group, there is one article in the files section that you must read as a beginner, Phil Harrington's article "All About Beginners' Telescopes". While you're in the files section also have a look at Phil's Favourites, a great collection of links.
The second group is Yahoo! Groups: Binocular astronomy, a group for people whom like to explore the night sky using binoculars. In this group everything concerning binocular astronomy is discussed.