What is the difference between windows xp and windows xp media center?

Media center is a version designed for HTPC use and therefor has built in support for tuner cards. Its designed around viewing/using on a tv with a remote though keybd and mouse will work also. On windows vista and 7 media center is included so you could psooible get a feel for it by using it on someones pc that has it. With XP it was a stand-alone product and i dont beleive you can get to the desktop to load other software but I'm not positive.