Then you'd be mad to go with the NewEgg solution. Dell's offering would include a single warranty, be properly developed to have good airflow (always hit and miss, more often miss, with home builds) and is pretty much guaranteed to "just work". Home build
machines need to work out a lot cheaper to be worthwhile, require a lot of expertise to get right and even then are subject to a fair bit of luck.
And I'd disagree about high end hardware, the more powerful the machine you need, the more important it becomes to get a system with well designed airflow and that's tricky with a case you buy by picking what looks nice in a webpage. And big OEMs put a lot
more effort into checking alternatives, such as the overall performance characteristics of hard drives etc, which the specs on NewEgg aren't really going to show you.
I disagree, as would anyone who has built custom systems. I don't even consider mass market boxes when planning a new system.
If your goal is to have a cheap box that performs decent go Dell. On the other hand, if you want the best box that meets your requirements build a custom system if you have the skills.