Memory usage on 64-bit OS

[alcattle]

to OP:right but also wrong,
The only software controlling amount of RAM is the OS. Windows this case. The base 32 - bit OS only sets up 4 gigs of memory locations. From that number, the OS uses some, drivers use more so you end up with 3.5 gigs or so of usable RAM. Programs take memory from that amount.
64 bit OS will allow a huge number of locations, forget the number but more memory then your PC can hold.