The second one is slower. THe first one is too much $$$ for what its worth. Either buy a 5900 non ultra for $200, then OC it to 5950 speeds, or buy an ATI Radeon 9800 XT for about $20 more than the 5950 Ultra.
AAhhh, what the hell, go for the 9800 XT, screw all the other cards, you seem like someone already willing to spend near $400.
Or, if you are willing to wait a little bit, get the new 6800 U for $500 wich will smoke every card out today.