Firefly is REYES is it not ? In which case like all other REYES renderers it should be rendering internally in float (or 32 bit per channel)

As for Poser's RAM usage, i'm with kawecki on this, since i also don't know what the hell is going on in the render. Either its not freeing the RAM properly, doesn't have a proper scene BSP in the first place or has some mem leak somewhere. Cause in both Lightwave and XSI (the 2 other apps i use with poser) i can load up 20 James high rez meshes with full 3k textures and the render does not cross 700-800 MB in RAM. In poser even 4-5 such figs start running into double that.

Hope they work on this in 7, cause throwing RAM or 64 bits at the problem is no solution. Even if Vista lets you cross the 4GB barrier, most non server boards in the market have hard limits on the amount of RAM they let you add. Many wont even run in dual channel mode after 4GB or will slow the RAM down to 333 MHz or even lower.. So adding more and more RAM is not as yet a very good option IMO.