Parts wise, it sounds like a really solid machine. I would lean to say ~1300 is probably about fair, although one could probably find a better deal if he looked. I think the most important thing when it comes to buying used PC's is if you know the seller or not.
It's not a bad machine, and probably fairly priced for already being built and tested.
That said, if you're buying a new computer, $1300 can get you a lot more than that if you build it yourself. There's a lot of wasted money in that build (such as the 1000W PSU, VelociRaptor, sound card) and some lower quality/performance parts (PSU, case, GPU).
I'd take a shot and compare what you can get for you're actual budget to this build...
Mad is right there, it was early this morning and newegg didn't have any CPU+Mobo deals up for some reason, so I couldn't beat prices. I'm not too keen on PSU's, but I'd have to agree that PSU does seem iffy. Really though, that's a very solid machine if you're not ready to build your own. Hell, my 2007 rig runs every game at max with playable framerates