If you just want speed, I'd go with a Western Digital hard drive. Currently, AMD's probably the fastest processor brand over all, but Intel's got a new processor coming out that'll kill any of AMD's current processors, so you might want to wait a while long if possible.
Motherboard brands, epox and DFI are some of the better brands out there for AMD. Definetly go for the nForce4 chipset too. If you go with intel, I don't know what the better chipsets are right off, nor what will be compatable with the new processor.