If you want to zoom in to a specific area on your image, use the Navigator palette. Hold down Command (PC: Control) and click and drag in the Navigator window to "select" the area you'd like to zoom in on.
Author of Photoshop Finishing Touches, Photoshop CS2 Help Desk Book, co-Author of Illustrator CS2 Killer Tips. Speaker, Trainer, writer for Photoshop User magazine. Featured on a number of training DVDs and one of the "Photoshop Guys" on Photoshop User TV. Adobe Certified Expert and Instructor, Photoshop CS4. Passionate about photography! 2009 Inductee into Photoshop Hall of Fame.