The phenom and Athlon are the same core , but the phenom has an L3 cache .
It seems to me that an athlon x4 640 has about equivalent performance to the i3 530. So why not use one of those? It would be cheaper than the Phenom , and combined with a good 880G chipset motherboard [ so you dont have to buy a graphics card immediately ] you could also afford the 4 gig of RAM now
This sounds like a good idea