David, you have a lot of sympathy from a fellow bionic person. I had my left knee replaced in March of 2001.
Don't worry too much about hospital food. To begin with, you won't feel very much like eating for a while, and then you'll be out of there in a couple of days. I had the surgery on Wednesday and was back home Sunday afternoon.
Make sure you do the therapy, as painful as it may be early on.
Best wishes for a quick recovery.