We upgraded every
computer in the place at the end of last year. For most we went with
Dell's, they're rock solid for most uses, and they let you customize components a bit.
My design rig we went with a VRLA Tech workstation. They're on the same level as Signburst out of the box, solid, bulletproof, you can upgrade spec the base models to your heart's content. I didn't get anywhere near the best of the best, and it's more than most will probably ever need. Came in right around 5 grand and worth every penny, plus I know exactly what's in it, and did before they built it.