Hi John. beren suggested a program the other day for stacking images and I'm finding it really easy to use. Its called imagestacker, it does stacking and averaging (good for darks). It stacks multiple 2 and 4 mb images in nothing flat. I haven't tried it with anything bigger but it might be worth looking at.
http://www.iceinspace.com.au/forum/s...ead.php?t=2455
That's about all it does, no waveletting or adjustments I haven't tried it in slightly rotated images but it might work.