I'd agree that the GT240 is the faster of the two. Since at this level Dx11 is irrelevant, the GT240 is the better buy.
However, I'd recommend neither. The HD5570, HD5670, HD6570 and HD6670 offer more performance than those for less.
And dont worry about PCI-E x16 1.0, 2.0, 2.1 or 3.0. They are all forward and backward compatible, and the performance difference will be negligible in a budget card.