Here you can see a couple of 3d tours around the rooms in the castle, so you can admire the architecture. Of course, it's not the same furniture as in the Middle Ages, but it can give us an idea of the luxury, and the enormous differences between a king's or noble life, and a peasant's.
http://www.royal.gov.uk/virtualtours/Flash%20Panoramas/low_flash_004.html
http://www.royal.gov.uk/virtualtours/Flash%20Panoramas/low_flash_005.html
http://www.royal.gov.uk/virtualtours/Flash%20Panoramas/low_flash_003.html