I gotta be honest, I'm almost considering a Q6600 again now. After adding in the price of another rad for my watercooling it's tempting to save the cash. 775 setups are going for very little money now with more and more people upgrading... I dunno, too many options!
I would say... go for am2+, maybe GA-MA790X-UD4 or something, 955be and 8gb ddr2. Then, in good times buy yourself mbo with sata 3.0, some speedy ddr3 and SSD. You can then sell this old eight gigs and mobo.