The question about what kind of computer you should look at really depends on a great deal of factors. First, what is your expected usage for this computer? Will it be a heavy-duty design system, running large format printers, cutting vinyl, or just basic office tasks? Next, what kind of budget are you working with or expecting for this new computer? There's a huge difference in recommendations for a new computer in the $800 price range and the $1,800 price range. What type of software are you planning to use on this computer, and are there any other specific needs or preferences, like small form factor or storage capacity needs? Do you have a preference on custom-built or pre-built, such as going with a Dell or HP system compared to having something custom built by a small shop?
There are a lot of factors that go into the decision as well as the recommendations. If you are looking only at a pre-built big name brand system, then I'd suggest either the HP Z-series workstations, or the Dell Precision series workstations. If you want to go with a custom-built configuration, you're going to get your best bang for your buck, but need to have someone reliable who can assemble it and support it for you, and ensure that you're getting the high end quality hardware for your money and not just the junk bottom rung hardware. If you're looking at going custom-built, then you might contact Casey with SignBurst for options down that route, but I can also give you some basic ideas of what kind of hardware range you're going to be needing but need some answers to the questions above first.