This is why I'm posting this question.

I would prefer the pricing and power/$ of AMD processors but Intel
processors generally run cooler requiring a cheaper case, PS, HSF,
electric/AC bill and it's quieter. These will be placed in one small room.
(Of course energy consumption probably isn't a meaningful point until the
day we can talk about inexpensive flat-panel monitors.)



I don't have a clue on the current state of motherboards.



Usage?  Arcade games and some educational apps on Red Hat.



Video cards? I suppose some brand that supports linux *well*.

I generally like Newegg so if you have an impulse to check them out and make
a suggestion we will probably actually use your advice.  I'm getting
pressured to order this stuff today.

Thanks.