If you're going to be building a brand new i7 in a year then the Q6600 is probably enough for you once you overclock it. 3.2Ghz on air should be fine with a decent cooler. 3.0Ghz is "Free" with the FSB speed of the motherboards (Q6600 = 1066, so up to 1333 of the mobo is 'free'). though I would consider just keeping your 3.8Ghz dual core until then since you won't likely see that big of a difference with CF 3870's (depending on what resolution you're at).
Also consider that the Phenom II is coming in Q1 and so far looks like it's going to be a crazy overclocker and should have a good impact on prices.