Best Mobo for Overclocking AMD AM2 5000+ Black

Im building a new pc on a budget and my work horse is going to be The AMD AM2 5000+ Black edition because of its overclockability and Price/Power ratio. I've been eying up the Asus M2N-SLI Deluxe SLI mobo for $131, but sense this is a budget machine would I be able to get the same overclocking bang for my buck with say the Gigabyte GA-M57SLI-S4 which rides in at $80-90? The rest of the build mainly consists of a 9600gt card because of its power/price: which concerns me because its a PCIe 2.0 card, even though its backward compatible with v1.0 should I consider a 790fx or alike chip set because of the performance gain from PCIe 2.0?
I know you can't SLI on the 700 series chip set, but my budget is $500-600 so SLI isn't an option and you can still run a single Nvidia card on the 700 series chip set.
Thank you for your help

I'm in the same situation as you are. I just ordered the Asus Crosshair II Formula for my Asus 9850 Black Edition and now I need to decide on a motherboard for my wife's Athlon 64 X2 5000+ Black Edition. She had a MSI and it died on her so now she wants more bang for her buck. She also has 2 EVGA 9600 GT with PCI Express 2.0 X16 and wants to be able to use as much as possible with chances of SLI in the future. The Asus AM2 boards with 590 SLI chipsets will run at 16X16 in SLI but the 570 SI and the 500 won't. I thinck she is leaning towards the Asus 590 SLI series because of the highend features and the SLI 16X16 for the video cards. From what I've read on a lot of posts is you don't loose that much when comparing PCI Express 1.0 X16 versus PCI Express 2.0 X16. Google pci express vs pci express 2.0 and just read through some of the hits. Manufacurers will tell you there is a huge difference and some tech experts say there isn't much real world difference. If you don't really want the SLI mode the Asus M2N-E seems to be a good board but the overclocking leaves a little to be desired. The M2N-E SLI and the M2N-SLI Deluxe SLI only allow 16X8 in SLI mode. the M2N32-SLI Deluxe Wireless Edition is on newegg for 179.99 and is a 590 SLI chipset with a bunch of features including overclocking. Check it out and let me know what you get. My wife has dessided on the Asus Crosshair for the 5000+BE for $229.99 and it is supposed to be a great overclocker. By the way the new Asus motherboards that have the 780a, 750a and 730a are AM2/AM2+,PCI-Ex. 2.0 and nvidia. There are only 3 out as of today the Crosshair II Formula(which I just ordered) the M3N-HT Deluxe and the M3N78-EMH and they are all AM2, AMD and nvidia! There are about 3 more or so coming soon from Asus!

Sounds like you have everything figured out! I've read some reviews on the other 570 chipset Asus the M2N-E that say it is horrible for overclocking and the M2N-SLI is decent for a budget overclocker but has the same chip. My brother has the M2N32 SLI Premium Wifi Edition and it has the 590 chip and is a monster for overclocking but also puts off BIG HEAT! You'll probably get more of a life span out of your set-up than I will mine or my brothers! Let me know how it goes after you get it done. You know how reviews from people can be, byassed. I hope it works for you!