is there a chart that shows the differences between .. let's say an aoa150 and a a150x? i have searched but i guess can't get the right search terms. also, what do the the four digits at the end mean aoa150-"xxxx"? also it appears some aspire ones have a 1.3 mp cam, while most have a 0.3, is there a list of those with one or the other? thanks!