Once again, if you buy these servers from "any" company, and the DC becomes unhappy that you are a file host, your whole project is gone, and all your money is gone. When you ask for their assistance in migrating, you'll be told to get fucked.
If you are using this file host, as you said, for your own websites only, and it appears in any way shape or form that your websites and the file host are connected, you will open yourself up to a serious charge. (a user here named To0 hosted files on his own servers, while operating a warez website [different servers] and has just been released from Federal prison)
Be very careful about what you plan to do here. It's too easy to lose every cent invested, or open yourself up to a world of legal issues, unless you know exactly what you are doing.
You will need a dedicated 1Gbit line, and from the appropriate file host friendly company, this is going to cost you ~$800+ per month aside from the server. Quad Core, 8GB RAM, 16x 1.5TB HDD's, and a 1GBit port (at the right place) is about $2,000 per month.