One of the factors to consider in setting up a comprehensive system is the cost of each Media Director. The Viewsonic VMP75 is selling for $119.00 shipped which would be very reasonable for a MD in each room.....
Anyone use this or something like it for a MD?http://www.buy.com/retail/Product.asp?sku=215764450
This looks to be a closed OS device so the possibility of having it PXE boot and run the MD boot image is essentially zero. Look at one of the many low cost Atom/Ion machines on the market now... these start at about $200 USD and make really excellent MD's (and at a reasonable cost too)
All the best