7600GT is pretty darned fine. I can't talk about the x1650, but I've got no complaints with the 7600, personally.
x1650 is probably a bit better, as I think it's a more recent card, If the 1650 is considerably pricier, go with the 7600. If the prices are almost the same, I'd say err on the side of caution and get the x1650.
Also, there's only ONE driverset for the 7600GT. x1650 might have better driver support (not sure). If you get the GeForce, use only 84.66.