3/4 modern english and 1/4 1337speak
p is pronounced as a p
4 is pronounced as an a, such as hay, today, etc.
ee is pronounced as double ee's, such as "see"
Combined, P4EE is pronounced "Pay", which is what you do when you buy a Pentium4 EE.
I p4eed too much for this 32bit extreme piece of crap, I should've bought an A64.