actually they might be right. corporates might be looking for cheap PCs, but they prefer Intels. AMD is small compared to Intel. Infact, reports say that AMD is not being able to compete coz it cannot make enough CPUs. And than there is an issue of serving customer complaints. It all needs infrastructure.AMD maybe cheap and fast, but so is Linux. they will pick up definitely but Dell cannot be blamed for now.
Depends on what you want to do with them.
The Chipsets are equally important. My Dell Machine has the Latest Intel 925X chipset and has really fast IO (SATA harddisk and DDR-2 RAM). A blazing Fast CPU otherwise perhaps just gets you good benchmarks on performance while you may not see any real utility value of those speeds(I think they will be good for some of the high end games).
I just made sure that my CPU was atleast 3.0 GHz as the WMV-HD Video playback requirements on the microsoft site recommended this configuration to playback the 1080p HD videos.