gtx 460, 550ti or 5770

hi everyone. im considering upgrading my desktop pc, since currently im runnnig flight sim on my mac book pro through hdmi to my 24 inch LED at 1920 by 1080.i have a choice between 5770, 550ti and 460 since i want to upgrade the cpu to atleast an i5. furthermore, i'l be running the following addons in fsxtraffic xREXPMDGand i might buy a few airport addons.in my experience, traffic x realllyyyy slows down my laptop. im able to get 20 fps if i turn down eveything except global resolution and aircraft cockpit.so basically i want to know which i5 would be the best for me, since im not going for a very high end machine, and which card would be the best. im thinking gtx 460 gives the most bang for the buck. im really confused abt the cpu, since that really boosts up fps in fsx since its cpu intensive.. but wil a 460 be an overkill? or can i get eveything to high on a 550ti with an i5