Question about hosting

Hello everyone- I need some expert advice so I turn you to all! :) I'm am currently in the process of making 7 web sites using PHP and MySQL backend. I'm porjecting that all of these sites combined will get a million plus hits a month easy when it's all said and done. What I'm wanting to do is to put the database on it's own machine and put the sites on a different machine to reduce the cpu load. However, I'm not 100% sure this is the best option. I know there are a ton of variables to consider with this situation and I'm trying to figure out the best way to go so I don't have to redo it again. I'm thinking with the traffic these servers are going to incur if they are on one computer then I should probably have a dual CPU with a gig of ram or more and two hard drives.. Once CPU for serving up the pages and once CPU to run the db. Also, one HD for the db and one HD for the pages in trying to get the most performace out of one machine. Some of the dedicated options that people have thrown to me are in the range of a 450 CPU with 512 Ram and 30GB drive. I don't think that with so many pages being served that this system will handle it. Any suggestions? Thanks, jay