You can't upgrade the processor. The processor on this unit is soldered on the main MLB...it wouldn't be worth it to invest in a new MLB and Processor to upgrade it. Who knows what kind of firmware issues you would have. Cheaper to just buy a new one.
The Core2Duo CPU will not be soldered to the board, so you can replace it. The motherboard you have is 667Mhz FSB, so the 800Mhz CPU will not run any quicker on it. You'd be better off getting a 2.33Ghz Core2Duo.
You can't upgrade the processor. The processor on this unit is soldered on the main MLB...it wouldn't be worth it to invest in a new MLB and Processor to upgrade it. Who knows what kind of firmware issues you would have. Cheaper to just buy a new one.
where did you get this idea from? all of the intel Mac Minis do not have a soldered processor, people were upgrading the core duos to core2duo before apple officially released C2D.
to the OP: just one thing you may want to think about if you haven't bought one already for this then pick up a used core solo mini, since this will be the cheapest you can find and there will be no difference once the processor is upgraded.