Well...it depends.
Pellets tend to have a slightly higher utilization rate (10-15% depending on whose book you read), so a slight increase in hopping when moving from pellet to whole hops is often recommended.
However, if the recipe calls for a specific AA, you also need to correct for the actual AA of the hops you're using (except in the case of flavor/aroma/finishing additions).
So, if the recipe calls for 2 oz of 5% AA pellet hops, and you have 5.5% AA leaf hops, applying both corrections results in a negligible difference.
I'm sure that was really confusing, and I'm sorry. Someone else may explain it better.
Also, we're talking about very small variations here, so if you're unsure, just stick with the basic recipe number of 2 oz.
Here's a decent reference article:
http://www.bodensatz.com/staticpages/index.php?page=hops