Yeah. Pretty much you want to get your hands on as much as you possibly can. But, you could probably do some decent work with 1.66 dual core. Just remember with reason every time you add something new to the rack your chewing up more bandwidth on your processor. So, optimise, optimise, optimise. Make sure your mixes are only running any thing they need it will help you keep your latencey down around a workable range. Same goes for any VST's you use in your sequencing software (IE. sonar, logic, cubase, or what ever). Every VST will be eating processing bandwith. When I got started I was using a single core 1.2Ghz 64bit Athalon with 1 gig of ram. I was able to run some pretty hefty mixes because I got really good about optimising my mixes, and progressively turning up my latency. So, early in the rough mix while I was still recording my latencey was set to 5 or lower. Once all my parts were recorded I'd raise my latencey a bit. It sucked to have to work like that, but you gotta do what you've gotta do.