Quoting from page 22 of the PoserPro Reference Manual:

Poser Pro ships with 2 versions of its FireFly render engine: A 32-Bit and a 64-Bit version. Traditionally computers utilize a 32-Bit Operating System, which can only address a limited amount of memory. However, there is an increasing amount of computers that are equipped with a 64-Bit Operating System. If your computer has a 64-Bit Operating System, Poser Pro will use its 64-Bit FireFly Render Engine to access as much memory as possible. To utilize the 64-Bit FireFly Render Engine, you must select Render in Background

still hooked to real life and enjoying the siesta!
Visit my blog! :D
Visit my portfolio! :D