I ordered from AVADirect a few days ago and can update in 2 weeks or so when it arrives.
They had the best selection of parts and a very low price, perhaps the best/cheapest of all the online builders. The only other online builders that came close were CyberPowerPC (equally cheap) and DigitalStorm (good reputation), but CyberPowerPC didn't have the selection of parts and had pretty poor reviews. DigitalStorm had good reviews and okay parts selection, but had a very high price. All other online builders had other problems (bad reviews, significantly more expensive, or bad parts selection).
AVADirect had one of the best online reviews and records with the Better Business Bureau, but they didn't have as many total reviews as many of the other bigger builders. There was one very dissatisfied customer, but AVADirect had gone online to try to explain that they'd tried everything to make the guy happy but that he was just a difficult person to deal with. Who knows, and it was just one guy. AVADirect seems very serious about customer service on their webiste's mission statement, and when they didn't have the GTX 470 I'd ordered, within minutes their customer service guy Misha offered to replace it with another brand at the same price.
I will update once the computer arrives if I can remember...
edit/p.s.-- I think it's probably clear that the guys from ADK on this board are more serious about Premiere CS5 and study/research how the software works with their systems more than any of the other online builders. They're more expensive than a place like AVADirect, but I have a feeling there would never be a CS5 problem with the systems they build.