Unless he meant if you were going to drop some extra money on higher speed memory, you'd be better off dropping it into a better VGA card, I have no idea.
If he meant dropping extra money on faster memory means having to drop more money onto a better VGA card as well, then I really have no idea.
The main practical advantage of having higher speed memory for gaming is presumably to match a moderately to highly overclocked CPU with a high FSB speed.
I suppose if you bought a budget CPU with a lower clock speed that had to be significantly OCed via FSB so as not to bottleneck your GPU, you might have to buy higher speed memory or memory that is reputable for overclocking as well.