The Acer V3 is better. This is because it has a 3rd gen core i7 processor AND a 2GB NVIDIA 640M card. Mainly from a gaming perspective (if the comp handles gaming, it'll handle the other basic features without a problem), you can game with a good processor and an average card (like the second option) but you can't game with an average processor and a good card (like the first option).
The 650M is an entry level class 1 card, which will play many games on medium settings just fine... however the i3 processor will be the weak point. The i3s came out around 2009, and since then, a lot has changed in the technology. Besides, this i3 is a dual core processor, but the i7 is a quad core processor. The i7 has been specifically designed for gaming, as it's structured to handle a much heaver load. So your aggregate output would be a lot more with an i7 and a 640M than with a i3 and a 650M.