Yeah, this is the first game that really uses 256MB on card that reallys dont need them... generally, 256MB are starting to worth it since 9800XX/5900XX/6800XX, X800XX, 7600XX, X1600XT, 7800-1800++++++++++++++++++++
If you see... for exaple a 7300XX/6200XX/6600XX/X300/X600/X1300/X1600pro which 256MB is just marketing, because those mem going to be 256MB DDR2 instead 128MB GDDR3, so the 128MB will be faster, and the card cant handle 256MB of textures a good FPS anyway. The High end cards always uses a good extra amount of memory, because its high AA and AF, HDR, capability.
The same happends if you see a 6800XX, X800XX, 7600XX, X1600XT which 512MB... But high end like 7800/7900/X1800/X1900 may uses it, but only when using filters.
I say this because I see to many people wasting their money on 9200/5200/5500/6200/6600/X300/X600/X1300/7300XX which 256 or 512MB... and this is the only game that going to use this extra amount of memory... (well Vietcong 2 also allows you to load everything to card memory

)
Anyway, I also running which adveffects on a 9600XT 128MB card, I only having some slowdown on explocions...