@Michael_Schwarz

No, that is not correct. The limitation are give by more thinks as only the processor:

1) prozessor (not the problem, then all processors since 5 year or so, are all 64 bit processors)
2) the the motherboard (motherboards for privat user can use since one year more the 4 GB RAM. At the moment maximum 16 GB)
3) The OS (operation System). If you use a 32 Bit OS on a 64 Bit processor, the processor only use the fist 32 bit of his 64 bit. So that you can only use 4 GB (but realy you can use only 3.5 GB for example by XP 32 Bit)
4) Aplication if you start a 32 bit application on a 64 Bit system thay can only us 4 GB per application (becurse it runs in a simulation of a 32 bit system (in a 32 bit Environment), and per application why every application get his own 32 bit Environment:

by
White_Wolf

P.S.
Sorry for my bad englich.