I initially paid about $670 for mine in January of 2010. Since then, upgrades have raised the total to about $1,157. Yeah, so I've put $1,157USD into my PC over 3 years and 3 months. This doesn't include the monitor, as I already had one. And I received Windows 7 as a Christmas gift--conveniently, the month before I ordered the PC.
It still runs everything I want to play well, except The Witcher 2 (it's perfectly playable, but I wish it ran a bit smoother). I know it also struggles more than I'm comfortable with in modern MMOs, which just gives me another reason not to play them, which is probably for the best.
I'm planning to splurge on my next build though (no idea when that's gonna be; probably will build in time for The Witcher 3 for maximum prettifulness). #YOLO

. But, yeah, I have the money to burn for the first time in my life, so I figured that I'd like a top of the line gaming PC at least one time in my life. So, might as well do it soon while it's financially feasible. Cause, who knows, I might be dirt poor in X years.
Some considerations for the OP (that EBay page you bought from was difficult to read)
-From what I've read, that processor is weaker than an i3 processor. It's basically an A10 chip without the integrated graphics. It might suffer in CPU intensive games (Planetside 2, modern MMOs).
-Your power supply is 450W (I think), and it's probably a cheap one. So if you ever upgrade past a 5770/6870/7770/560/450/650/ graphics card, you'll need a better one. I have an off-brand 550W PSU that hasn't exploded yet, so gambling is an option as well.
-A 6670 is a pretty weak GPU at 1080p. Just FYI. I know you don't care, but there you go.