I use panorama factory
www.panoramafactory.com I've been using it for years, don't know how well it compares cost or performance wise with the competition. It gets upgraded on a regular basis, so presume it's on a par with others. It is undoubtedly very, very easy to use. Can be used to produce ultra wide images or even QuickTime Virtual Reality movies. Open this file with QuickTime (which you may already have integrated into your browser):
http://homepage.ntlworld.com/duncan....use%20Wood.mov
Move around with mouse+left button, zoom in and out with shift and ctrl
This sort of subject is about as difficult as it gets for panorama programs to stitch without seeing the joints.
P.S. I should perhaps add that if you're stitching a large number of dSLR files together, whichever program you use, it will take a while on anything but a high end PC.