Most office computers are Intel simply because there's rarely another choice. Most of the big computer manufacturers ship only Intel in their corporate line of computers, because that's what most of the corporate buyers "know." Remember that saying, "No one ever got fired for buying IBM"? It's the same with Intel: it's the "safe" choice.
But the truth of the matter is that AMD processors are FAR better for the $. The types of problems AR15forfun describes are motherboard and/or chipset (controller chips on the motherboard) problems, not CPU problems. Most likely, the problems were in VIA chipsets, which were very buggy a few years ago (they were popular because they were cheap...).
There are currently 4 companies, each with several chipsets, that are available for AMD CPUs, and the architecture has been around long enough that the hardware is very stable.
The bottom line is: if you're spending YOUR money, you buy AMD. If you're spending company money, you probably won't have a choice but to buy Intel.
-Troy