What's needed to run a 5850?

Hello. I was wondering how much of a pc would be needed to utilize a 5850 properly?
I'm currently running a 4870 in a p35 based system with a 3,4ghz c2d. Would it even make a difference to upgrade (other than power savings)? After all I have pcie v1 and only two cores.

Another slightly unrelated question - would it be possible to run sli with a 4870 and 4890 (in an x58 system)? (I assume not) They're almost the same after all....

1) To utilize a 5850 properly? Honestly, a PCI-E x16 slot and a PSU that will run it. The better CPU you have will just allow it to perform better. Regardless it will be a big improvement over your 4870. A single PCI-E x16 1.1 slot has enough bandwidth for a single GPU card. You won't have any issues.

2)You can run a 4870 and 4890 but the 4890 will clock down to the 4870 speed. You may as well get a 2nd 4870. (2) 4870's will draw quite a bit of power, but will perform better than a single 5850.

-A side note, I had a 4870 and tried doing crossfire but had ALOT of heat issues. There was only a single slot between the (2) PCI-E x16 slots so the cards were right up against each other. The top card would hit 100C and crash my games. I could have rigged up some kinda of crazy cooling system with a fan or two, but I decided to sell both cards and get a 5870. BEST decision I could have made. I just wish I did it right off the bad and didn't take the ebay and paypal fees to sell the cards.

go for a 5870