I have included a three way comparison with P35/X48/P45 to illustrate the differences between the chipsets.
Immediately, we can see that the P45 is similar to the P35 in many ways, although there are a few key changes.
P45 supports up to a massive 16GB of memory officially, whereas the X48 and P35 support 8GB each.
Curiously, Intel don't list any support for their own Extreme processors, something which I suspect is an error in their literature. There appear to be more errors in the table of supported
FSB/memory configurations too, once I find out the correct details, I will update this part.
Surprisingly, there is no official support for 1600FSB CPUs, just like the P35.
PCI-E 2 is limited to either a single 16x slot, or dual 8x slots.
Another error in the table appears to show that the ICH10R has less features than the ICH9R - I will find out more on this and update as needed.