JC writes: "For a variety of reasons, the Boot Camp Assistant sometimes fails to let you do the things you want to do. It doesn't work, for instance, if your drive is already partitioned. Many early adopters partitioned their drives before Boot Camp, hoping for an eventual dual boot solution either from Apple or elsewhere. In my case, I used Boot Camp to repartition my hard drive, then used that partition to install another copy of OS X for a test. Unfortunately, Boot Camp Assistant refused to reclaim that partition when I was done. That's 20GB down the drain!"