it some what depends on the method of projection... if i'm presenting it off my laptop i do mine @ 1024 pixels wide x 768 pixels tall (16 bit colour - 92dpi) but then again, that's just me.

it also depends on the graphic style, are you asking "bitmap" images for background? flat colour data charts? 3d graident data charts? a mix of all three?

anyone else want to add?
retrocity