I understand your cynicism in your post, regarding memory. It is over emphasised as a value of 64 bit, and I would guess that the majority of users in the world rarely need more than 2gbs!
However, there is quite a lot more invloved than memory. The first, maybe nothing to do with performance at this stage, is that we are definitely moving into 64bit technology, as we moved from 16bit. It is the way forward. New software and hardware, in the very near future, will only support 64bit.
We have 32 digit streams and 64 digit streams. Twice as much data can use the stream, in 64 bit or, to put it another way, the same data can process at twice the speed.
But it has to be kept in mind that, in computers,to take full advantage of the 64 bit...