Are you looking for an easy to use and free panoramic image stitching application? Check out Microsoft ICE (Image Composite Editor), its one of the easiest to use and free panoramic image stitching programs I have found for Windows.
For those that don't know what a panoramic image stitching application does, it takes a set of overlapping photographs of a scene shot from a single camera location, and creates a high-resolution panorama that seamlessly combines the original images. For more information on Microsoft ICE, check out the product page for the application.
Operating system: XP, Vista, or 7 (32 or 64-bit)