Maybe you should focus on building your product and utilize a service that will be able to scale better than you will be able to do on your own. Check out Amazon Web Services http://aws.amazon.com/ . There are a lot of big sites using their EC2 and S3 services...you should check these out. That said, I am not a scaling expert, so if you're hell bent on doing it yourself, good luck! I'm sure somebody on here will be able to offer you "do it yourself" advice.