The video card is almost totally irrelevant. It would have to be really ancient to make a difference to Poser 5. My experience; 512M of RAM is barely adequate. By Windows XP the OS is using enough that it doesn't take much to start disk swapping and Poser gets horribly slow (but XP is more stable). So I'd go for more RAM. (Poser 6 uses OpenGL for some features and the graphics card does make a difference there.)