I decided not to buy the first one because pentium is very weak compared to both i3 370m and i3 380m. So price will decide which to choose because I don't know exactly what the pricetag of Acer Aspire 5742G Xtreme GT is. But I think it's the same as the a Acer eMachine E732G where I live.
if Acer Aspire 5742G Xtreme GT is same price as eMachine E732G I'll be very surprised. But if that's the case get the aspire, it's a better machine out of 3 of them, if you cannot afford it, emachine will do fine for you