9800GX2 or HD5770?

[DoubleStop]

I can get these two cards for roughly the same price, the 9800GX2 will be used vs a new 5770. Which one is better? I do not game too much, mainly looking to upgrade for Starcraft 2. I've heard the 9800GX2 will out perform the 5770?

 

[DoubleStop]

Will the 9800GX2 be compatible with my current setup?
Gigabyte H57M-USB3 Mboard
Antec 500w power supply (Antec Sonata III 500)

I've heard it may need special cables to hook up to the power supply?

 

[aklinc]

i have 2 9800gx2 in my setup with the latest drivers and i have been playing starcraft 2 well compleated it on them. the cards are fast but the game constantly crashes the the drivers for the card's i have try to run them as a single card, dual sli and quad sli. no matter what i have tryed it wont run the game properly i have try so meny builds of the nvidia drivers its unreal i just cant get these cards to work with starcraft 2 i have desided to opt for 2 Asus GeForce GTX 465 and run them in sli and gonna hand down the gx2 to my other setup all so with the cards cooler sandwiched between the cards its hard to cool them and you cant get 3rd party coolers for them you can get a water block but i have trashed 2 setups with water cooling never again