Vallejo paints do not have amny of the warm browns and greens, but Games Workshop paints have awesome colors for both of those.
I just grabbed some Vallejo's from a local store that is also stocking the butt-kicking Rackham/Confrontation miniatures. (I got the skeleton guy with the windblown cloak full of animal bones. He's soo cool. Here is a pic of someones interpretation off the New Wave site. ) I havent had a chance to use them yet, but I've heard nothing but good things about these paints.
Anyway, the clerk rumored that Vallejo will shortly be introducing a line of paints that mimics GWs line. (He had some specific name for the new line, alas I cant remember it.) I'm looking forward to that; there are certain GW colors that I am used to working with