How to make PAE at least working?

Have a laptop core duo ( 36 bit ) without EM64T, would like to exploit a whole 4GB RAM. Unfortunately be new to linux environment, but enough to quick install KDE, and setup it as default to boot in. Used to explore a little bit BackTrack5, in an instruction in the net, there is simple procedure:
prepare-kernel-sources .. etc.
Tried that way, compiled enhancement ( choice 64GB ), after rebooting still BT5 saw only 3GB.
Decided to try Kali installed, in that system I installed everything that has in name:
3.7-trunk-pae
and
3.7+46+kali1
except that so-called xen.
And the same result, there still is no effect.
Could someone help explaining how to 'activate' PAE. Would like to mention that be windows user. Had tried PAE in vista, it just says that there is 4GB, practically it reaches as much as linux, means 3GB.
Supposedly my processor, that is equipped with PAE support, could exploit 64GB.
Maybe there is similar procedure like the one delivered by www.backtrack-linux.org, that uses: 'make menuconfig' ( or better 'xconfig' instead that is much comfortable ).
Recapitulating: have 4GB RAM, a laptop equipped with standard Core Duo ( 36bit ), thus probably am limited to 32 bit environment (?), each linux I tried did not give opportunity to use 4GB, just 3 is, want to know what to do to exploit the whole RAM.
P.S. Need it 4 planned complicated calculations, in windows have problem with some application that in general needs ~700MB, but momentary needs much more. The effect is as time 2 time refuses saving my work.