Thanks for the comments. As far as separating DB from Web, we've done it here and I tend to recommend it so the OS doesn't have two apps fighting for memory more than anything. CPU as well, but with SQL, it doesn't want to give up memory.

I'm not sold on consolidation in smaller environments, but as you grow into tens or 100s of servers, I've got two words for you: Power and heat. They might make you rethink consolidation.