I hear what you're saying, but not sure it applies across the board.
I've worked for this small charity for two years, it has 60 desktops or so. Ranging from 4 year old maxdata machines through to 6 month old Dell's.
Getting a stable buying plan is almost impossible given the rate we're growing (50% p.a.), I therefore think we've got to buy the best hardware available at the time. To do otherwise simply doesn't make a good investment...
Back to my pc/chassis decision. Looks like a Dell Optiplex 745 small form factor with 5 years...

































