they are totally dif boards with totally dif chipsets the abit is alot newer and like you said it uses ddr ram, so you will need to buy new ram, cant use the pc133 stuff.
a better comparison would the kg7, the epox 8k7a, the gigabyte 7dx and the asus a7m266. they all use the amd 760 chipset
if you want a tried and proven board very stable and mature the a7v133 is a good choice, if you want the newest and greatest then you need to look at boards with the amd 760 chipset or some of the boards about to come out with the sis 735 or the nvidia nforce
the sis and the nvidia will probably totally dominate anything that is out right now, including the kg7