This is a very old thread, but here goes: About Macs and RAM - yes OS X will be allocating RAM dynamically (somewhat like Windows). In the older versions of the OS, you could allocate the amount yourself (I always liked this). In Windows, if you don't have enough RAM to run the two (+) applications you are using, it uses virtual RAM (read Windows Swap File). In other words, it uses your hard disk as RAM: This is THOUSANDS of times slower than real RAM (Since OS 8 the mac also does this by default - the GREAT thing is, you can easily turn it OFF!!!). And it is why PCs hard drives are constantly churning away as you use the computer. The bottom line is: there is no substitute for the real thing. On a Mac or PC, I think 500 MB of RAM is probably the appropriate amount for running Poser. And RAM is cheap.