I wouldn't scoff at that. The Windows environment and open spec of PC's don't allow developers to wring out all the juice the way they can on a fixed console platform. Also, both companies are banking on their data transfer optimizations and caches to make a huge difference in performance.
We'll see for ourselves, but it has always taken PC's a little while to catch back up with a newly-released console. TFLOPS and clock speeds don't tell the whole story.