Isn't the obvious answer, 'because it wouldn't be low end' ?
3.06 has 2 cores while the i5 has 4 cores (i think?) if thats true then the 3.06 will be faster for apps that only take advantage of 1 cor but the i5 will be better for multi threaded apps
thats only true if the i5 is quad core, if ur looking to buy get the i5
They were saying on the last episode of macbreak weekly that the quads can throttle down two cores and boost the other two depending on processing needs, so there may not be any difference between the two on less demanding apps.