Edit: Sorry didn't read that you already bought the parts. Doesn't seem to be much wrong with what you got? if you already have the cards to slied together then do that, no point in getting the 6850 then. Other than that the build looks good.
Hi hartastic, OCZ Golds have been having a lot of problems of late. If they're working already, good for you. Else if you haven't opened the packaging, get 'em replaced with Kingston HyperX, Corsair XMS3 or G.Skill Ripjaws.
Also as far as the PSU is concerned, I'll prolly go with a Corsair, Antec, Silverstone, XFX, OCZ, CoolerMaster ahead of a Raidmax on any given day. Get a non-mod one if you wanna save some money.
If you do decide to go with a single 6xxx series card, get a sub 650 Watt PSU. 750 will be way overkill.
Sorry for the double post, but if you're using older HDD/ODD make sure they're SATA, or you'll need to buy IDE cables separately. (1 will prolly come with your mobo. You'll have to buy the 2nd one if both your older drives are IDE).
If you are planning on upgrading your videocards later you should get a psu thats overkill for what you have now. I had an Antec 500w but when I wanted to buy two GTX 470's I had to buy a new psu and replace all the wiring in my system making it a huge hassle to upgrade.