According to a few sources who are selling both Nvidia and ATI, as of January 2009 people simply want more Nvidia than ATI.

At this time, 55nm based Geforce GTX 260, GTX 285 are outselling Radeon HD 4870 and 4850, while the dual chip Geforce GTX 295 is outselling HD 4870 X2. People simply want the faster one, and at the moment, it's Nvidia.

February is usually a bad month for graphics sales, as seasonally people buy graphics cards before February and January was rather good for Nvidia simply as people do want 55nm chips more than they wanted 65nm GT200 ones.

ATI has to impress its customers, to get some much needed attention, and its 40nm performance card is likely scheduled for early Q2 the earliest.