how do i make the header image auto-resize (instead of repeating) and auto-proportionate (so it doesn't look too elongated) in Dreamwaever 8? is this even possible?
It's not possible in any form or fashion, outside of perhaps embedding it in a Flash. JPG images are raster (pixel) images, so when you expand or contract them, you're not expanding all the lines and borders that comprise the image; you're expanding a series of 1x1 squares. Take a JPG and try doubling one (or both) of the dimensions and watch what happens. That's why it's not possible.