Conditionally display fields in admin

[Larry Martell]

I have an admin form for a model and based on the value of one column
(either as it is in the database or as it's entered or changed by the
user), I want to conditionally display or not display other fields. Is
there a way to do this natively in the admin or do I have to write
some javascript code. If I have to write some js code, where would I
put that code?

Thanks!
-larry