best way to determine if a user has modified a record

When a user edits and submits an existing record I need to perform
conditional logic based on whether the user has actually changed any of
the values.

What would be the best way to detect changes? Thanks.

http://svn.viney.net.nz/things/rails/plugins/acts_as_modified/

@person = Person.find(:first)
@person.modified?

-Jonathan.

Perfect, thanks.