That Gateway is a good machine. However, the power supply is limited, so if you decide you want to upgrade your graphics later on, you'll be in a similar boat as you are now.
This pre-built machine may be worth a look. The graphics card is much more powerful than the 5750, and the liquid cooling is interesting.
http://www.newegg.com/Product/Product.aspx?Item=N82E16883229169&cm_re=cyberpower_pc-_-83-229-169-_-Product
Now, while I know I'll sound like a broken record here, I'd suggest investigating the 'do-it-yourself' option. It's not terribly complicated, and seeing as you're tinkering with a Vee Dub, assembling a PC, and getting it up and running will be a piece of cake in comparison.
For the same price as that Gateway, you can actually get a considerably more powerful computer. Or, you can get similar specifications for cheaper. For example, I quickly pieced together on newegg.com, an i5-750 system with a 5770 and a 1TB Hard Drive for $914.92; that doesn't include the 90 bucks in rebates. You could save even more money if you go with an AMD platform, which will get you a CPU faster than the Intel i5-750 for cheaper.
The benefits of building your own are that you can cherry pick components that are tailored to your use, and you get top shelf components. If problems with components arise, then you are covered by warranties, and you can get support from the manufacturers.
A few of us have built systems like siegen, Dodgefan, PurdueGuy, JamesBond and myself, so you'll have plenty of 'local' help if you're willing to build your own.