PAE isn’t a “hack”, it is an integral part of the modern Windows 32bit kernel (used by Windows 2000 and 2003 Server - Enterprise and Datacenter editions only) - the problem is that only these versions of the kernel are licensed to use it.
Microsoft mostly advertised it as a feature of the server editions such as Windows 2000 Server and Windows Server 2003, and only then for the more expensive levels (Enterprise and Datacenter). However, even Windows 2000 Professional can be configured to access memory above 4GB using PAE.
Obviously the mobo has to support PAE.
PAE works very much like expanded memory (LIM EMS, for those of you who can remember it) on the old 8088 - Windows 7/32 can handle it and can allocate as much as 4GB per process. It remains a 32bit OS, though one that can theoretically address up to 64GB.
MS disabled the use of PAE in most 32bit kernels for four reasons,
1) It "wasn’t always stable" (this is questionable)
2) Licensing strategy
3) Intel HD Graphics driver was not compatible and Intel didn’t want to fix it (AMD and Nvidia HW/drivers mostly work fine) and
4) They quite reasonably thought that a full 64bit OS was better and stabler.
There is a good discussion here:
Licensed Memory in 32-Bit Windows Vista
The kernel “adjustment" (OK, hack) is simple and there are automated tools to do this if you like.
As they say, your mileage may vary since this is not an approved procedure.
Windows itself works fine, but unless you work it on a fresh install (recommended) be prepared for some driver incompatibilities (surprisingly few I found).
Having said that, I have an installation of Windows 7 that is quite happily using 16GB of memory with no more instability than an unmodified kernel (it did take a bit of tinkering though).
My advice?
Switch to a true 64bit OS
Mac
PS: Any 32bit Windows OS will be much happier with 4GB of RAM
If the OS is short of onboard RAM then many of the benefits of a SSD will be lost