i run alot of large programs... and even if they are 32 bit.. they run TREMOUNDSLY better on x64... and the OS os alot more stable than i thought it would be. even the built in 32 bit emulator....
(I'm using XP Pro x64 Edition)
I think it is the most stable Windows yet. Just wish more drivers and 64-bit programs were available, but with Vista down the road that will hopefully happen soon.
Still, as soon as Vista is released, I will upgrade. In fact if I hear the later betas are very stable, might even upgrade early.