got too excited, I shoulda read all the way to the bottom :

12. Is the 32-bit architecture going away? Should I use the 64-bit
architecture instead?

The 32-bit architecture will be replaced by the 64-bit architecture
effective with the Pro/ENGINEER Wildfire Release on SGI UNIX platforms
only. The 32-bit architecture may eventually be replaced by the 64-bit
architecture on other platforms as well. PTC will continue to support
32-bit platforms until technology and market demand dictate a need for
change. For those customers working below the 4GB memory limit, the
32-bit architecture remains the platform of choice if available.