Microsoft ICE (Image Composite Editor) is an amazing and free tool for stitching together panorama photos. Unfortunately, the download links at Microsoft’s website no longer work.
Here’s a link that still works on Microsoft’s website: ICE for 64-bit Windows (probably the right one for you) or ICE for 32-bit Windows
Here’s our copy of those files hosted on our site, in case they break in the future: ICE for 64-bit Windows (probably the right one for you) or ICE for 32-bit Windows