@Bluebeam
The limit is 4Gb, i.e. 2^32 (4,294,967,296 bits / 4 Gb). That's where the "32" in 32-bit operating system comes from, a 64 bit operating system can address 2^64 bits of memory (18,446,744,073,709,551,616 bits, 4,294 Petabytes) without any tricks.
This is system memory only...