As has already been answered by Otlecs;

  • You can't upgrade from 32 to 64 bit, you must perform a clean install
  • PM Keyclone and have you key reallocated

I upgraded from 32 to 64 bit last week and I've not expierenced any issues (touch wood). There are a couple of applications out there that won't install on a 64 bit OS, but in most cases you can simply edit the installation file with a tool called Orca and remove the OS requirement.

Why are you looking at upgrading to 64 bit?