OC.com speculates that the C1 1.8As should hit 3GHz+ without too many problems.

I would personally get the C1 with the lowest multiplier, which would be the P4 2.26, with a multiplier of 17.

The next best choice would be the 1.8A/2.4B with multipliers of 18. Of course, if the 1.8A hits the same speeds as the 2.4B then it makes little sense to buy the 2.4B. We will just have to wait and see on that.