I have a 500mhz AMD k6-2 and my brother has a 200Mhz PII and the difference in working with Bryce is vast. I'm so spoiled with my computer. Sometimes we swap so he can play a video game and within 5 minutes I'm ready to throw his computer out the window! With the mathematics involved with a torus' or circles (pi and all that greek stuff)your computer is making incredible amounts of calculations and has to rewrite all this to ram and the hard drive each time...even with 128Meg. believe it or not your file is probably right at that size so much of the data has to be swapped back and forth to the hard drive and then into RAM. you have to either get a faster CPU or more memory. I'd go with the CPU.