Keep in mind your '09 has Hyperthreading on that Quad Core, so OS X will see 8 cores, similar to your 1,1 - the raw multicore performance may be slightly lower when you check up on the CPUs, but the 4,1 is almost twice as good as the 1,1 for occasional gaming, and though you might not notice it that much, is probably much better for casual use due to faster RAM access. Though I remember you saying previously that you don't have an SSD - a PCIe SSD will do wonders for either machine, but will perform better in your 4,1 due to the increased PCIe bandwidth.
The Architecture advancements alone are worth switching to the 4,1 - let alone the future upgradability and OS X support. There's just no reason NOT to use the 4,1 imho.
EDIT:
I would suppose the reason it was thrown away was the faulty video card, but I'd run some stress tests for a few days to make sure that was the issue. Don't want a logic board dying on you if you choose to sell your 1,1.