well... if you put a 3.06Ghz in there you'd get 2.3Ghz
..
there is a 400FSB 2.4Ghz P4 I believe, so you could get that one.
Why do you need to upgrade? It's just buying another 400FSB chip will mean buying yet another new processor if you upgrade again later on, whereas getting a new mobo now means you could get stuff like dual channel RAM & 800FSB, and be able to support the first couple of prescott chips when they arrive.
---
<font color=red>The preceding text is assembled from information stored in an unreliable organic storage medium. As such it may be innacurate, incomplete, or completely wrong</font color=red>