First Time Builder Seeking Advice

First time CPU builder here. My old PC died recently, and having replaced every par but the mobo and CPU in past comps of mine, I decided to make my own. I hope to make it a fairly powerful, if not incredible, gaming rig capable of handling games for the next few years on decent settings. I'd also like the ability to hook it up to my HD 1080p LCD TV.

Now, I've bought my processor, its a AMD Phenom II X4 940 Deneb 3.0ghz AM2+. I bought it packaged with Windows Vista 64bit SP1 Standard Edition.

Unfortunately, in finding a pairing mobo I've hit a bit of a jam. I'm looking at these two:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Now, I can't figure out which to get, as I'm a little over my head in the technical jargon. One reviewer claims the GIGABYTE mobo doesn't run in full PCI-E 2.0 power. And I don't know if the other would be a reliable brand.

Besides that, in terms of graphics cards, I've been continually eyeing this:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Seems powerful, but I wonder if its more than I need or too high a price for power.

I'm at a loss for what other parts to buy...

If anyone would be willing to afford me some help and advice building this PC, I'd be very thankful for the guidance. I'm trying to keep the rest of the PC components under $600, but I don't know if I've bought a processor that sort of necessitates more powerful/expensive components.

Thanks for any help offered this wearied soul!