Nice map GP. I totally agree with you. The antialiasing is only going to make minimal difference. With PNG it would add a little but with JPG anti aliasiing would likely drop the size a little ! But this challenge is more technical than artistic. Knowing how to get an image compressed is more important than anything else including artistic merit. Its going to depend on the image but I would favour JPG but theres lots of maps that would be better under PNG. I would think that Xara would help out quite a bit on this challenge.
Again, nice example - ill start the thumbs even if this one changes.