Need adivce on a good new computer build

I'm buying a new computer, for 600-800. Anybody have any recommendations?

I want it to be overall fast, should be able to run basic games like runescape and maybe minecraft, must be stable.

I'm going to build it probably.
Must be parts available in Canada

(If the build does not include windows 7, then the max budget is $700, seeing as windows 7 is $100)

Thanks

 

Here's a quick one I threw together. All I didn't pick out is a case and optical drive. You can just get windows for free, so that shouldn't really be a part of the budget... This build will play almost anything and I'm aware it that every part isn't the best value necessarily, but a couple of parts I picked based on personal preference, specifically the HD. If you want me to take the performance down a notch and suggest some more solid parts, I can do that too.