I have 2GBs + 160GB harddrive as well.  Someone wrote in past threads, that no matter how powerfull system you have, poser will only use so much to a max limit written in the software. I still get out of memory error once in awhile to,  doesn't speed up the renders and bucket size doesn't help. "lower bucket size" (when it is at 64). Not like gaming, it will everything in your system.