My personal favorite:
Check out the reviews at the bottom of the web page. Better than McArdle's book IMHO.
Exercise Physiology: Theory and Application to Fitness and Performance by Powers and Howley
Exercise Physiology: Energy, Nutrition and Human Performance by McArdle?
Or should I just splurge and get both?
If you don't mind used, check out amazon and ebay. I've gotten several used books that were in perfect condition!
Then you don't feel guilty about getting both