A formula can only affect the cell it is in; that is, it can't set a value
in some other cell. So, if I correctly understand what you want to do, you
will have to put a formula in that "next cell" which looks at what was
selected from the drop down (in other words, what the value is of that cell)
and sets its own value accordingly. You still haven't given us enough
information for a more complete answer, but the information Chip posted
should be of some help in creating the formula for that "next cell".
Rick