A few people recently found that the X800 Pro VIVO model is basically an X800 XT with BIOS restrictions. By installing the XT BIOS you get all 16 pipes of the XT! I'm sure the manufacturers might correct this soon, so if you have $400 to throw down on a video card you should definately get one. Note that this only works for the VIVO version and not the standard X800 Pros. The X800 XTs are currently $600-$700.. so this is quite a penny saver.
Dunno if this violates the TOS, sorry if it does, delete it if it does.