Microsoft.com defines a tablet as "computers powered by the Windows XP Tablet PC Edition operating system, and equipped with a sensitive screen designed to interact with a complementary pen. Tablet PCs are fully-functional laptop PCs.
You can use the pen directly on the screen just as you would a mouse to do things like select, drag, and open files; or in place of a keyboard to handwrite notes and communication."
The Latitude XT starts at $2,499, not cheap by any standard.
According to CNET, the Latitude XT comes with a 12.1-inch LED-backlit screen, a 1.06-gigahertz Intel Core 2 Solo processor, 1GB of memory, and a 40GB hard drive. It can run on Windows Vista Business edition or XP Tablet Edition. The whole device weighs 3.57 pounds, and has about 5 hours of battery life.