[ejwells]

Given the choices listed (Dell, Sweetwater, ADK), I'd go with Sweetwater.
Sure, you're paying a bit more than if you built it yourself, but you get service from Sweetwater, generally directly from the guy who designed/built it.

In the past. I'd always been OK with spending the extra money to have a computer custom built. Self building can have it's snags...faulty hardware is not all that uncommon, which can have the potential for headaches and delays.

Certainly, your best bet (monitarily) is to build one yourself, or to buy all the parts, and have it slapped together by someone that knows what they're doing.
That would be my route if I were in need of a new computer now.

There's lots of great help on these forums for self builds, offered by guys that have built the best/fastest PCs known to the world of audio production. Many of the folks that hang out here have set the bar for PC builds, and many custom PC builders (Sweetwater and ADK included) have taken cues from them.