For stitching software, you can see what people are using in the poll at http://nodalninja.com/forum/index.php?topic=62.0. For spherical panoramas, Autopano Pro and PTGui are front runners. You can download trial versions of both and decide which suits you best. Depending on how you want to display your panoramas, there are additional packages that may be needed, such as Pano2QTVR, Pano2VR, Flash Panorama Player, Immervision Pure java player, DevalVR etc. But first you need to learn how to produce a 360x180 equirectangular image.