That would also be a Northwood.
KevDA and sakor1 are both right on.
Right now, Dell is not offering Prescott's. Originally, I think I read somewhere that Dell was waiting for the Prescott to release the iXPS, but since there were heat issues, as well as no real speed gains, initially, they went with Plan B, to intro the iXPS with the Northwood, this would also be for the 9100, as well.
I know that Intel will continue to push the Prescott, because they believe this will take them beyond, speed-wise, the Northwood.
But, they will also use what they've learned from their Xeon Core design, and adding the 2MB of L3 cache on the Northwood, and calling it an "Extreme Edition."
The Prescott offers 1MB of L2 cache, instead of 512KB.
Very soon they will introduce a 'faster' Prescott, that will be 1MB of L2 cache PLUS the 2MB of L3 cache (from the EE/Xeon Core), this is where the Prescott will start to show signs of being faster, having twice as much L2 cache, along with the 2MB of L3 cache. This will also be marketed at the hardcore gamer market, video editors, and the like.
But there is still that 'heat' issue, with almost 2-3 times as many transistors on a smaller die size, I have heard they have resolved that issue, but I am not certain that they have resolved the heat issues or not.