All I can tell you is that the retail chain I work for sells 3 times as many GC's as it does X-Box systems. And ever since the $99 price drop took effect, we have been seeling even more. Even our Ps2 sales have taken a dive. A serious dive. we have not sold a ps2 in almost a month.
Let me just say this, the company I work for is not the place one would usually buy a game system, where more of a "music and more" chain. It makes me wonder how places like EB and TRU are doing with their GC sales. Several of the TRU's near my home were sold out of GC's for about a week after the price drop.
However, I'll look for whatever numbers I can find, why don't you do the same BW?
(EB = Electronics Boutique, TRU = Toys R Us)