There is already a thread for this^^^
Honestly? You should try to build yourself, its not difficult and quite rewarding. If you have someone build you one they will rip you off, or if you go to some other place that sells them you will still get ripped off. $1000 is quite alot and you can build yourself a monster system. There are various resources and videos on how to do it, and the motherboard instructions basically lay it all out for you step by step with pictures and shit. If you ever built some legos, well its just that fucking easy, shit just snaps together.
But, if you are so hard pressed against building one, you could go the dell way...
And then buy a good video card and replace the shit one it comes with. This should have the 460W PSU so it should be good enough to power a good GPU. Also you will want to add a SSD as your main drive. So you will have to make sure you get the OS on a disk so you can reinstall on the SSD.
So you are still going in there and fucking with stuff. But this is pretty much the best deal you can get.
You could also call around locally, maybe there is some mom and pop PC shop near you. What you can ask them is if you bought evrything, if they would build it for you and at what price. Thats another way to go as well....
But seriously, just fucking do it. If you take your time, do it all step by step like the mo-bo instructions tell you to do it. You will have everything done in a few hours, have a better PC, quieter, you can then OC it if you want to (this is easy too), and you can now upgrade it when you want to. (new video card every few years....)