In a 32-bit operating system, memory addresses are 32 bits in length, limiting the total number of unique addresses available to around 4 billion—effectively capping the total amount of memory your system can use at one time to 4GB.
Why 64-bit Windows Doesn’t Rock So Much:
-You need at least 4GB of memory
-32-bit drivers don’t work anymore
-Some software breaks in 64-bit Windows
-Not all software benefits from 64-bit
64 bit is the future as is windows 7. I repeat I have never had any problem with getting hard ware, nor running just 2gig of memory, nor any applications while using it. So where these so called problems I just do not know.
I've mentioned it in another topic that I work with graphics intensive applications, so the more free RAM I have the better. And when working with 32bits I have about 1GB less memory overhead compared to 64bits. So it is more efficient for me to go with 32bits on 4GB machine.