Best. $800 gaming PC

Solution
The second build is a lot better. It is probably more upgrade friendly as no new processors will be made for the AM3+ socket and it is already a couple year old architecture.
There's a pretty big price difference between those two builds, but if you can afford the Intel one, I'd say that's a bit more robust. Also, I prefer Windows 7, but I hear Windows 8.1 is a fairly nice update and can be run in desktop mode (avoiding that touchscreen BS) and will be supported longer than 7. Overall personal preference.