It's really hard to say. I know that later this year Qualcomm is releasing the quad-core Krait, which will be used in some tablets to power Windows on Arm.
I will say this. Just about any desktop CPU will run circles around these ARM chips in pure raw power. A decent comparison would be Intel's Medfield SoC. It's loosely based on Atom, and is decidedly midrange in performance. It's also single core, with hyperthreading. That's the closest we'll get to a direct comparison I think.