[H] PCI V2 vs V3?

[DSinc]

Can anyone supply links to docs explaining differences, needs to 
upgrade, wants, other fluffabout
this?
I now run PCI-X 2.0. I am shopping new/replacement video cards; and, I 
find that most/all of the real
'want/nice-to-haves' now say PCI-X 3.0. Am I now stuck in yet another 
technology quagmire?
Thanks,
Duncan