Please keep in mind the alan wake demo seen recently in the presentation from intel, was on a Quad core q6600 overclocked by 1ghz with some pretty hard core cooling.. Whats that mean? Well if the developers are using a quad core, alan wake is definately going ot use more than just a dual core..
I was in the same boat, i JUST pulled the trigger on a quad core.. Why?
1. I play to rip it up in Crysis, Thats been said to use MULTIPLE cores (over 2 even)
2. ID tech 5 (now titled Rage) will most DEFINATELY use multiple cores, carmack has even expressed no interest in PPU's *physics processing units* and intends to just off task that particular item to an available core in a multi core processor
3. Even half life 2 episode 2 will use up to 4 cores (For weather effects and such)
4. Many other games, including UT3 and others, are going to be using Quad core in the next 6-8 months if they ship on time)
5. I like to play WoW while i do other things like surf up to 10-15 other websites, Watch movies while i grind, download in Emule and other such things.. having 4 cores mean i have a dedicated core to the game, maybe a dedicated core to watching a movie, and left over processing power for whatever may need it..
I feel i made a good choice. (i have not built my system yet, parts still coming). I feel the q6600 is a better choice than a bit more speed.. Look at the benchmarks for something like Lost planet in the cave demo, the q6600 spanks the 6850 hard core.. yes true in all other benchmarks for games that do NOT use the multiple cores over 2, the 6850 has a pretty good lead on the 6600, but its never anything more than 10-12fps.. which yes is a good amount, but its not EARTH shattering. and IF those games ever get multi (3+) core support, i expect those ratio's to swap in favor of the q6600..
i'd advise the 6600 for your prediciment.