I also have 2G ram and experience crashes with complicated render settings. I find that for anything I have done to date, 72 dpi always works. That is okay for web production, but for prints, not so good. I fuss with the render settings until I get the highest quality that will not crash.
If increased ram is the answer, I know what I am getting for christmas... (Hmmm... no, I already put a Wacom tablet on that list, birthday, maybe....?)