First Build--Any Advice?

[Narinerd]

This will be the first time I build a computer, and after talking with a friend who has built several, I came up with this build, but I thought I'd post it here to get more advice/criticism. I think everything is compatible, but I've had some trouble picking out a gpu, so I will post a few of the options I have been considering. I really don't know to much about this stuff yet, so bear with my inexperience if you can.

cpu: AMD Phenom II X3 720
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103652

mobo: MSI 870S-G46
http://www.newegg.com/Product/Product.aspx?Item=N82E16813130590R

cpu fan: COOLER MASTER Hyper 212 Plus
http://www.newegg.com/Product/Product.aspx?Item=N82E16835103065

RAM: Kingston HyperX Blu 4GB (2 x 2GB)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820104203

HDD: (x3) Seagate Barracuda ST3500413AS 500GB 7200 RPM 16MB Cache
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148701

optical: LITE-ON DVD Burner
http://www.newegg.com/Product/Product.aspx?Item=N82E16827106289

psu: OCZ ModXStream Pro 600W
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341017

note--I could upgrade to a 700W unit if necessary

case: Antec Three Hundred Illusion
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129066

gpu: ZOTAC AMP! ZT-50402-10L GeForce GTX 550 Ti (Fermi)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814500194

or ASUS ENGTX550 TI DC/DI/1GD5 GeForce GTX 550 Ti (Fermi)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121435

or SAPPHIRE 100314-3L Radeon HD 6870
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102948

 

[DXRick]

First step: read this thread.

 

[Narinerd]

I will, thank you.