ASUS is the brand you want. This research is a little old now but I imagine they still have the lowest malfunction rate. http://www.electronista.com/articles/09/11/17/reliability.study.has.apple.4th.place/
Three years ago I bought an ASUS for $1000 with 17" screen and an i7 and a like a B-grade graphics card and I'm still extremely satisfied with it. Probably not replacing it for another year at least. Only game I've been unsatisfied with is Witcher 2 which was too stuttery at lowest settings (I only really enjoy games if they're at 60fps).
My girlfriend got an ASUS 15" with an i5 and built-in graphics around Christmas for I think $500-$600 and she's extremely happy with it (I'm pretty impressed with it too), I don't think we've tried anything super graphical on it, but sims 3 and portal 1 run perfectly at default good settings.
One thing I especially like is the vent on the left side rather than the bottom or back.. My laptop's is powerful but somehow very thin compared to most good laptops I see, and as long as I use an air duster on the vent every six months, it doesn't really get hot.
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