Actually in gaming there is no comparison at all.
As you can see here, (the 3670 is almost the same in gaming as 3650) the gts450 has almost 5 times the framerates (3650 APU 22,39
vs GTS 450 104,17
):Tom's Hardware charts
With this difference in performance, since you are thinking of gaming, and in multitasking are somewhat the same, the answer is pretty clear:Intel G620 + Nvidia GTS 450 1G DDR3
ps: Don't mind about the DDR3 of the gpu, it looses a bit in performance but its not something so great...