Download Microsoft ICE (Image Composite Editor) here
• Open up Microsoft ICE
• Open up the folder where your photos are located
• Select all the photos of a room / area and drag-and-drop into the gray workspace area of Mircosoft ICE.
• Play around with the various tools/settings for the desired results. 9/10 times you will end up with a perfect panorama if you've taken good quality shots. Still not getting the desired results try the Panavue Image Assembler (trail version is available).