To be completely honest with you, if you are planning on doing serious HD video editing, then your are going to want to look at ether Nvidia's Quattro line, or AMD/ATI's FireGL line of cards, as that is some heavy stuff there, as yes, more video memory is better for what your doing. On that, if that not so much on the HD editing, than i'd suggest ether an 8500 shouldn't work out to bad for your other areas of interest. However, of the choices you've given, i'd go with the 9600, as is has a lot more memory.