By doing as Blue mentions, it still keeps one from using other things within the worksheet such as formatting, inserting/deleting rows/columns, and sorting, just a few to mention. If you didn't want to prevent these kinds of things, but still want to protect that one cell, then there is no real way of doing it.
Ronald R. Dodge, Jr.
Production Statistician
Master MOUS 2000
When the going gets tough, the tough gets going.