Inside the Shuttle XPC System there is space for one 5.25" device and at least one 3.5" device. These are housed in a detachable chassis which makes installing and removing storage devices a breeze. So in terms of internal expansion the machine is already filled with devices right out of the box.
For those who want access to the world of high performance 3D graphics, the Shuttle XPC System includes an PCI-Express or AGP expansion slot for high end video cards. If you are working with digital video, nothing can be more important than this.