On the one hand, we'll cut Shuttle a little slack with the XPC P2 4800X. By shoehorning an Intel X48 chipset into a small form factor case, not only do you get support for Intel's most recent Core 2 Extreme quad core chips, but the computer also features two eSATA ports. If you're a designer and you want a fast little system that will accommodate speedy external storage, you might find something to like here. The case itself is also unique because it comes with a built-in fingerprint reader behind a front panel door.
But on the other, more important hand (the one with the rating on it), Shuttle positioned this system against the Falcon Northwest FragBox 2. That system lacks the X48 chipset, and thus cannot use Core 2 Extreme CPUs. It can, however, support two graphics cards via AMD's CrossFireX. That's important for gamers, and moreso than an Core 2 Extreme CPU for those who want to play at high resolutions.
Technically, the X48 chipset can support more than one 3D card, as well. Only, not in this Shuttle. By opting for a smaller chassis than the FragBox 2, this Shuttle system has only a puny 450-watt power supply. That means it can't supply enough power for more one 3D card. Shuttle also doesn't offer the Radeon HD 4870 X2 as a two-chip, single-card upgrade option (unlike Falcon Northwest, which will sell you two of them).
Sorry, Shuttle. We liked that little Linux system from a few months back. We're also working on our review of that newer one. We just can't recommend this gaming system.