Re: Help with Buying
find an AMD processor if you like gaming or a intel for mutlitasking. i go by that even though AMD can multitask and intel can play games very well also. i belive that all those you linked have onboard video except the second one. onboard is fine for typing, music, and internet browsing, but for movies and games and video editing you will want a good card(something you can upgrade without having to scrap your entire rig.) advice you might hear a lot is to never buy a prebuilt computer, to buy the parts and build it yourself. i can either design you one (list the seperate parts) or find you a good value, but first i need to know what you will be using it for, your price range, and do you need a mouse/keyboard?
also, personally i'm reluctant to buy any computer parts off eBay.
EDIT: i'm not as familiar with ATI as i am with NVIDIA but the i looked up the video card in the seond one and it is ok but fast becoming low end.
So it Goes.