Overall in the real world,the GTX 570 is a more powerful card (however uses more power). The pre built is not exactly fantastic, running on an outdated AMD processor and a sub-par motherboard. The PSU brand is unheard of and would probably break the system in a few days, and the case isn't exactly beautiful.
Your build however is very well conceptualised and thought out, with quality and new parts.
Overall, your build would outperform the pre-built easily, however I recommend a single change. The GTX 570, whilst powerful, is an older generation card, and you could probably pick up an AMD 7850 for around the same price. They perform fairly equally, however the 7850 will overclock in a much easier fashion, and require less power overall (cut down on those bills lol).
Anyway, I wish you luck, but please don't buy the pre-built haha!
Thanks for the fast replies everyone! I know the custom built one seems better to most of you here, I'm just worried because I have no prior experience to computer building. Hopefully I plan on doing a bit more research before diving into it but I'm glad you approve of the parts!
It is surprisingly simple to put the parts together and there are tons of tutorials online that will provide assistance. To me the most difficult part of first time builders is attaching the power/reset button from the case to the mobo.
Yeah, I just built my first last weekend. All went smoothly, and like zooted said, the hardest part was ataching the power/reset buttons lol. Sadly I had a faulty BD Drive and SSD so had to take back to Umart (Australian). They refunded, as any good company would.
I'm pleased to hear that you're going with the custom, and wish you all the very best!