Hard to say. Q6600 is still a nice processor. What software or games do you play?

I play anything from first person shooter, adventure and RPG game..basically game with great graphic..I do alot of video encoding and picture editing also...with 23" 1080p monitor and currently my Q6600@3.5ghz which seem to have lost it stability with occt stress test...over one year ago it can pass every stress test...that why I'm thinking of changing my cpu to x6 since its so cheap

Honestly the Q is probably fine..but

For serious video encoding the i7 930 trashes a x6. Also for PS+multitasking+just about everything it is superior

http://www.bit-tech.net/hardware/cpus/2010/04/27/amd-phenom-ii-x6-1090t-black-edition/10

it is $200 from microcenter if one is near you-

http://www.microcenter.com/single_product_results.phtml?product_id=0331303

Or on newegg $270

Also unless amd comes out with something better soon than x58 is more future proof. Intel is going to introduce some 6 cores of its own at a more reasonable price than the 980x far superior to what AMD has to offer. In addition I think AM4 is not too far off~1 year. while x58 is not being replaced till Q3 2011