jon, with the memory surely if youve got 256mb rather than 128mb then you can hold twice the texture or lighting information...
surely this can only be a good thing, especially in doom3 with the per-pixel shading? woulda thpught that in a game ike that that having the extra memory would mean you could move up a resolution over the smaller memoried versions
bear in mind tho the last time i knew feck all about graphics cards was when the geforce1 came out and replaced the

TNT2 Ultra

my did i wish i had that card over my 3dfx banshee