[CentOS] To PAE or not to PAE...

Hi,

I was wondering if anyone would know the cons of running a PAE kernel...?
I have a 4GB pc and was wondering if it was worth going the PAE way to gain 
those exta 700MB...
In the past, I heard that these 700MB were normally reserved for bios or chipset 
stuff...
And that running in PAE would slow down some processes.
By the way, I know 64 bits would solve this dilemn but right now I am 32bits...

Thx,
JD