[Blarg]

One reason for a gamer not getting a prebuilt machine from a maker like Dell is so he can put in a power supply adequate to handle the load that having two SLI video cards demands. Power supplies are notoriously underpowered on most major brands, and they aren't the kind of thing most people feel comfortable about replacing. They also come in varying sizes, and makers like Dell have been known to have non-standard cases, so an upgraded power supply might not even fit in your case.

Since being able to have two SLI video cards will substantially prolong the power of a machine for a gamer, I wouldn't get any system now that didn't have SLI capability, even if I just got one video card to start with. And that means you're going to need a really beefy power supply. Ones that are 500 or 600 watts are common, and I've seen 500 watts being described as bottom end in terms of the power you might want or need.