almost all programs are 32 bit
The exception that you might use is Adobe CS 5 or later .
No other programs or games can use more than about 3.2 gig of RAM . EVER
Yes programs may move to 64 bit as operating systems did , but there is no real pressure to do so since it wouldnt actually improve performance .
You will NEED 64 gig of RAM in about 2036
but by then cpu's will be 3D organic blocks of jelly , and RAM will be quantum states in graphite atoms
so basically NEVER