I would rather have 4 cores, that run slightly slower rather than 2 that run slightly faster. Games like Alan Wake need a min of 2 cores, because each thread is so intensive (1 thread thread on a 3GHZ quad takes 1 core with 80 percent usage just on physics).
No doubt Far Cry 2, doom 4 and co will also love it, and RTS games likes Supreme Commander adore multi core, I noticed a massive difference in quite a few tasks from a 3GHZ E4300 to my 3GHZ Q6600...(which I know could go higher, but having a few issues clocking it with the motherboard I have currently).