1) shoudn't have any problem unless the program is frekin old/obsoleted one.
2) There will be some perfromance boost if the game/program was compile/made to run on x64 platform.
3) its worth if you are gamer/graphic designer and the program you use always utilize large amount of system memory.
and if your mobo/network adapter/GPU ect ect hardware is not-so-old one and have 64bit drivers.

This post has been edited by 1024kbps: Dec 25 2008, 07:12 PM