Already built PCs or Custom built PCs for Business?

Do you prefer Dell, HP, Gateway, etc. for business? Or does your boss have you build PCs from scratch to save money?

Personally, in my experience, I’ve ordered parts and built PCs for fellow employees in different divisions, but I couldn’t help wondering if ordering a workstation from Dell or HP would have better results in the future (warranty).

What are your thoughts?

Do you build a workstation to save the company money? Or do you go through a manufacturer to buy a workstations?