It seems the normal expectation is you purchase the whole device ready-built. Doing it yourself with your own hardware is certainly possible, but I suspect you will find few people will have done that.
There is no reason whatever to think home server 2011 might not support any recent hardware. The major consideration about the hardware side of a server is disk storage and it's secure backup techniques, (possibly cloud storage). Plus the network speed (wireless), and environmental and software security. Video and processor power are both irrelevant.
I am sure lots of people on this site will have built their own home servers, but will have done it for free with one of the major Linux distributions. I for one can see no reason at all for using a MS product as a home server.
I would suggest you briefly explain what you have in mind that makes you feel the need for a server at all. No doubt it is the sharing of a massive collection of games, films and music ? Plus the secure backing-up of them all. Be prepared for a deluge of people advising you to consider a Linux solution. I expect they are right too.