Joe Kane's Digital Video Essentials Series sets the benchmark for all other calibration disks. This disk is an updated version of his original, with menus which are much easiser to navigate. Much of the instructional material is re-used from the original disk, but some of the calibration patterns have been updated.
If you already own the original DVE, then you don't need to rush out and get this. I had calibrated one HDTV with the orignial DVE, loaned the disk to a friend and it never came back. I have since picked up three addiontal HDTV's (which needed calibration) so I got this disk. The new TV's came out much improved. When I re-ran the calibration on the original set, the settings came out virtually identical to the settings I had with the orignial Disk.
If you are in the market for a calibration disk, then this is my top reference. It's not the prettiest. It's not the easiest. But it is the best.