As redmoon rightly pointed out, if you're going to get a new cpu in a few years, you might as well get the e8400 now.
I would get the e8400, seeing as in a few years, the q6600's will have come down VERY significantly in price, and 3 years is a pretty big time to be able to scrape maybe $100 bucks together.
Better gaming performance now, and in the future, sell it for a couple of bucks, and invest in a quad for those 'future' games
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