OK, I gather from the previous posts that updating a monster should be done in order:
1. Look up the monster in the Compendium. That entry should include the old values plus any specific errata that has been applied to that specific monster.
2. IF monster = MM1 monster, then apply MM2 math and then MM3 math
3. IF monster = MM2 monster, then just apply MM3 math
Does that sound about right?
By the way, is the math changes brought on by MM2 found in errata somewhere or in the Monster Manual II itself?