Just curious here. I'm coming from the Windows side of things so don't bash me.
Do the web servers really require 2GB of RAM? Couldn't you take out 1GB from the www serves and throw them into the SQL servers, assuming the stick count works.
SQL is a hog compared to www, at least in the Windows world. Used to until I got laid off work on the admin department for an Internet based company. Admined two colos, 100+ web servers and the rest of the mayhem that comes with it.
New servers look great!