My number one gripe with gaming machines is the noise they churn out when they spin up. In my opinion its always worth to pay a bit extra when youre shopping around to get a card with a better than stock cooler. And with the new ATI 5000 series cards the only option you have other than stock is the Vapor-X (This will change in the future)
I run this in a fairy packed case with limited airflow but the temps still come out about 10C lower than a stock ATI 5850, and most importantly the noise is kept to a minimum, the cards fan noise not rising above the ambient.
Of course if youre interested in that kind of thing you could use this increased thermal headspace to add an overclock (The frequencies are already slightly raised on this model), of course the flip side is that you will have to run the fan speed higher.
Although the entire ATI 5000 series has an incredibly efficient design with low power consumption, and is not in the same league as the power hungry NVidia cards, I think its still useful to cut out as much heat and noise as possible.
I you are like me then I recommend you spend the extra and buy the Vapor-X version of the 5850.