Need help with a special JOIN

Hi,

asume I've got 2 tables

objects ( id int, name text )
attributes ( object_id int, value int )

attributes has a default entry with object_id = 0 and some other where
another value should be used.

e.g.
objects
( 1, 'A' ),
( 2, 'B' ),
( 3, 'C' )

attributes
( 0, 42 ),
( 2, 99 )

The result of the join should look like this:

object_id, name, value
1, 'A', 42
2, 'B', 99
3, 'C', 42

I could figure something out with 2 JOINs, UNION and some DISTINCT ON
but this would make my real query rather chunky. :(

Is there an elegant way to get this?