Hi Wayne,
We've built several systems with W7000, either with or without S400. Performance is very good, the card uses little space inside the computer and for rental purposes they turn out to be more (mechanically) reliable than the huge heavy Radeon based cards. Well worth the extra price compared to Radeon based cards I think.
As suppliers go, in Europe it's always available at one or more distributors, either as AMD W7000, HP W7000 or Sapphire W7000.
Jan