I am hoping to be a first time PC gamer next week. My budget is no more than $600.

I have asked around for a good build in my price range but want second opinions. Here is the build suggested to me before.

amd phenom ii x6 955 - $137
Biostar A780L3G - $50
Sapphire AMD Radeon HD 6850 - $150
G Skill Ripjaws 8GB DDR3 - $51
Half 912 Tower - $50

Still need suggestions on a power supply and a hard drive. I'm at $438 with that build. I have a 1.5TB external HDD so I don't need a huge HDD, just a relatively cheap one. I already have a 22x DVD-RW and a monitor.

Is that a goold build? Are there any other parts I will need (sound card or anything else at all?)? Thanks in advance. I'm a little overwhlemed trying to build a PC for the first time. lol.