Correct Video RAM for Size Monitor

A few years ago when eveyone was using 15″ monitors the standard was about 2MB of RAM for video card memory. Then when the 17″ became standard, 16MB seemed to be the norm. I remember someone giving me a rule of thumb on this but I can’t rememeber. Now that 19″ monitors are being specified…what should I use 16, 32, or 64. My thought is the more the better. Any ideas??

Thanks,

Andre’