To stitch and upload a panorama from Windows, you will use Microsoft's panorama stitcher, entitled Image Composite Editor. (We all just call it ICE.) You can download it from Microsoft Research here: http://bit.ly/microsoftice
Hopefully that helps.
I don't want to give the impression that panoramas are bad, but photosynths are actually a leap beyond panoramic stitching, because photosynths are capable of matching images together even when the camera's position is different between photos and in a photosynth, a sparse 3D reconstruction of your subject will be generated.
Panoramas are great for a continuous field of view, but a single panorama just isn't as compelling for many of us as the ability to link multiple perspectives in a synth.
Thankfully, the day is approaching when Bing's upcoming Read/Write World will make the synth vs. pano argument moot by linking pano to pano and synth to synth, etc. http://bit.ly/readwriteworld for more.