It's possible using an old version of FreeStyle Dashboard, the feature was removed in newer versions i believe. Be warned though the loading times for a lot of games are very slow.
I created a tutorial on how to set it up here: Stream Xbox 360 games over a network (SMB) to an Jtag / RGH360 running Freestyle Dash
Obviously where i used Windows 7 to share the games you would simply put them on your NAS.
Thansks for your reply!
i have few games in internal hardisk and my xbox is modified, will my xbox work after updating it, and all my games will run.