> I'm not an expert
No offense dude, but, you're not. This isn't going to address the issue. The problem here is running 16bit apps and mixed apps with 16bit code bundled in with them.
PAE is physical address extensions. This means that you get multiple "windows" of RAM which means that you get to switch your view on which window of RAM address space you get to see. This allows you to see above 4GB which still using 32bit address space.
This doesn't allow 32bit applications to see more than 4GB natively, it doesn't allow the kernel to address more than 4GB (It's still a 32bit app after all), Citrix boxes can't magically take 20 times the amount of sessions, it's for large data storage applications.
So, if you have a 32bit app, it can only natively address 4GB of RAM, with the divide with Windows, this is half the amount of RAM you've got installed minus drivers. Graphics cards which have 1GB of RAM, will take 1GB out of the system so that the graphics drivers can address the RAM on the card.
This is great if you are MS, Oracle or VMWare and are fine with writing your own memory manager but writing a memory manager for allocations is a pain.
The poster was looking for a way to get old apps to work on a new OS, and honestly, getting it to happen reliably is a PITA.
If this is being done for a business, it's a bit of a dark art, all I can suggest is test test test test and test some more.