The shuttle will take 45nm chips - Q9440/9550 - the Q6600 that is a little old now - The newer ships will use less power which is good for a shuttle (i've built two shuttles before - my wife still uses one)
If you want the full 4GB you will need to look at running a 64bit OS
The built in graphics will be ok but not up to gaming...
Rather than a Raptor (again this is the older model) it might be worth looking at some of the 750/1tb drives they actually have great transfer rates acres of storage
http://www.newegg.com/Product/Produc...82E16822148274