I've been rendering a   (900 frame) 30 second animation at 800x600 72dpi. The sceene has 1/2 a million pollys, 200 objects and 9 lights. I can render it without problems on final, but I'm trying to use user settings. I have read the tutorials, and know what to adjust but as i push the # of traces up and overall quality up i get to the point where it will no longer render.  I'm using 64bit vista with 4 gig of ram. I know supreme quality is not possible, but my issue is just not being able to anticipate when too much is being asked. I can be 12 hours into the render before I get an out of memory error, which will usually not be recoverable, and the file is not saved so resume render doesn't apply.  is there a better way of telling in advance that you are going to runout of system memory?

Strange it doesn't happen in the beginning of the animation, unless some objects with high res textures appear during the course of the animation? Is there some Poser imported animated figures?
One way of avoiding losing everything before the crash is to render to individual frames.

Can you render out to bmp rather than an animation file type?  That way, you can render smaller sections.  Say render frames 1-25, 26-50, etc.  Then, using a free program like Vurtualdub, make it into a movie format. 

This is the safest way to render an animation, but does take some post work to “assemble” the frames into a movie format.**  **Since animations can take days to render, by rendering to bmp or jpg each frame is saved when done rendering. Going with a movie format like *.avi or *.mov - if anything happens while rendering, you loose it all!

Where it runs out of memory makes sense too. It's right when the camera moves towards 3 large highly reflective surfaces, 12 wines glasses and our poser charachter and his head of hair. It seems obviose now that I could have just done some test renders of frame 660 to 700 and looked for the out of memory problem.
as for the render to jpg option that is the approach i will use on the next sceene. I'm living with a bug right now on 7inf 38524 that won't allow me to change file format on animations once I have made the first one. Vue stops responding and eventually needs to be restarted.

There is a new update for Vue7Inf at e-on.