that processor would run you about 110 bucks, so total you'd have 180-210 allowing you another 140-170 to spend on other things, dvd-writer you can get for 30 or less, hard drive - depending on the size you need they come cheap but think in the price range of about 70-80 for a good sized one.

so overall your prices should be dropped while you're not really losing too much in performance, i'm not sure any games take advantage of the quad-core yet anyway, just give them time and they'll drop in price too