I have has success with just about everything, but i use an ATI card
http://img514.imageshack.us/img514/1734/optionswm.pngI'm sure nvidia user will be able to help you out.
Some drivers i have used also made pso not use AA for some reason, so in order to keep this level of quality i have to use old drivers, maybe it's a similar issue with you, maybe a specific driver doesn't let you enable AA on pso, don't really know.