Can't decide on a motherboard

Hello, all. I've signed up specifically to ask for help with my 1st build. I've pulled the trigger on all the parts except for one - the mobo. Here is whats on its way so far:

COOLER MASTER Centurion 590
AMD Phenmon 2 x3 720BE 2.8GHz
EVGA GTS 250 512MB
CORSAIR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800
LG 22X DVD±R SATA DVD Burner
Antec BP550 Plus 550W PSU

I am trying to decide between two boards in particular:
ASRock A780GXE
GIGABYTE GA-MA780G-UD3H

But really, I'm open to anything in the sub $100 price range. I'm building this thing to last, but I have to draw the line somewhere, you know?

While I'm at it, would you guys be so kinda as to critque my build? I know its too late as the parts are already shipped, but I'd just like to hear some honest opinions. And if anyone is wondering why I went with the GTS 250 instead of a HD4850, it is because the GTS had what apparened to be a great combo deal with the PSU.

Why though? The ASRock is $10 less and has better ratings on Newegg, so I'm just wondering what makes the gigabyte superior.

I think I am going to forego Vista and just jump straight into the Windos 7 beta + 32bit XP Pro just to be safe. Also, I'm wondering if that board isn't going to be overkill. From what I've seen, the P2 X3 720 should be able to do 3.2 GHz without expensive parts. I appreciate the suggestions though. Just have to ask questions before throwing down big money, you know?

I did it. I pulled the trigger on the GBYTE 790x, and my bank account is not happy about it...God help us all.

Related question: With this hardware configuration, what would be a moderate OC on the 720BE that would be safe to leave on for a couple days with stock cooling. If it matters, the Centurion 590 has 1 intake fan in the front.