Business Dell vs personal Dell are two completely different animals/products.

Business Dell computers are designed for heavy heavy workloads, that take beating after beating.

Personal Dell computers are designed for average joes/soccer moms/college kids

Components within one another are completely different.

My office is an investment bank in NYC and we all use DELL PCs.
and no one turns off their PCs.
So do many other corporations in the city.
They all mainly use dell.
why? price and reliability

I personally have bought a number of Dell systems, including 2 Laptops, (XPS and Precision) and a dual Xeon workstation. They have been fine, but they are top tier systems. Most of the home user stuff they sell is pretty low quality. I setup hundreds of Dells for my University over last few years, and those business systems had a ressonable reliability record.
For most professional video editing work though, the HP XW workstations are clearly the best option. They are certified hardware configurations for running Avid, ProTools, Matrox, AJA, BMD and just about every other high end application. This gives you a lot of flexibility in what you can run on your system. I use a Dell laptop at work, but about 15 HP workstations. The commonality between the different generations allows you to migrate most periperals and such to newer systems as you upgrade.
And I am a big advocate of buying refurbished if you want maximum bang for your buck.
Just my two cents on that topic.