If you want the full frame and just under 13 megapixels, 5d will be your camera at $3299. The price will be dropping within the next 18 months if time is on your side. The 20d's will not be going any lower then they currently are, they got marked down as far as they could already so for any "new" version of the 20d, your going to be paying the price out now. However, if your looking to grab one slightly used, or used, Ebay prices should be going lower now with the release of the 5d.
All in all, I myself am always deliberating on the jump and am considering the 20d myself, played with the 5d recently and it was a fine camera, especially great feel with the BG-E4 grip on it, but I don't have that kind of wampum lying around, so the 20d and a BG-e2 grip for me and some nice L series glass instead with a 580 flash.
If you are going to be in the northeast come october, photo expo plus will be the first public display of the 5d.