I need help choosing GAMING PC

I have been looking around for about a week now for a gaming pc. I will be mostly gaming. trying to keep it under 1000 usd

I am stuck choosing between 2 pre-built systems. I will upgrade the graphics card later

the cyberpower PC gamer xtreme 1348 >>> http://www.newegg.com/Product/Product.aspx?Item=N82E168...

and the

HP Phoenix H9 1513t >>> http://www.shopping.hp.com/en_US/home-office/-/products...

both will cost me 850 with tax and free shipping included

OR

any other suggestions??

maybe building a computer myself. but i need a list of parts & cost that i would need

thanks for your help!