Any medium system users and POSKY V4 747s

Hello I have a medium speed setup ie P4 2.8 ,1GIG Ram and GForce 6600 card and get good results with FS9 .However i have tried some of the latest V4 POSKY 747s and find them to be performance hogs ie grey textures when cycling views etc and i cant change textures to DXT3 either (my normal fix)as this results in a huge lag when changing from 2d to VC view which for some reason DOESN'T happen when i leave the textures at 32bit which of course results in grey lag going to spot view ie CATCH 22.If you are medium system owner how do you find these latest POSKIES?PS I can still use the earlier models which are still fine aircraft so i am just interested in knowing.cheers Andy