Hardly. HP and Dell cover most of the same ground, from laptops to mid-size servers. And the consumer space has Apple of course, and the enterpise has...SuperMicro? It has been more or less like this for some time now.
SuperMicro doesn't sell pre-built machines. However, in the case of our small company, they have received the lion's share of the money we spent on high performance hardware in the past couple years, as we no longer buy pre-built machines for our cluster. We buy our desktops and laptops from Dell, though.
Same here. I looked at HP, IBM and Dell but the first two make you go through awful 3rd party vendors that seem stuck in the 90s and while I liked what Dell had to offer it was just too expensive unless you NEED the prosupport in which case it's not a terrible deal.