you're just limited to 4GB of RAM for each individual program running on the system
Sorry but this is not correct. Vista will report 4GB of RAM on the System Properties page but the 32bit version can only use 3.25GB maximum irrespective of how many applications you are running. Each app will however run in its' own "virtual memory" the total of which shall be ...... 3.25GB.
Worth having a read.
What is the max ram for Vista 32 bit? [Solved] - RAM - Windows Vista
Also, I would suggest you avoid the PAE switch. Want to see a performance boost, install the operating system on a SSD. The Samsung 840 EVO has a 3 year warranty (the EVO Pro had a 5 year warranty) and the speed increase will surprise you.