What are the best hardware, software, and design to network a small office? And why?

Many years ago, it was cost effective to build white boxes (generic computers that you can buy parts for and build them yourself). I beleive that today, it is more cost effective for a small business to go with a vendor such as Dell or HP. Computers can be purchased as well as leased. They have good warranties and the computers are reliable. The small business can then just contract services with a IT Business that focuses on small businesses to provide consulting, and limited computer hardware support.