Wow, this is an old post, but I am looking for the same thing. Closest I could find was the Dunkin Doughnuts replica font called Frankfurter.
http://www.myfonts.com/fonts/efscangraphic/frankfurter-sh/
it is pretty much exactly Don't Panic except it has rounded edges. I am still looking for something closer,but this is as close to the shape of the letters so far.
That one you have to pay for but here is a similar one that is free
http://www.fontica.com/font/dunkin__donuts
Edit:
I tried going here to upload the marvin pic (croped to just the letters) to see what it came up with and nothing that good just this...
http://www.myfonts.com/fonts/agfa/phosphor/phosphor/?s=DON%27T+PANIC&case=default
this one has the sharp edges but has a cut out in the middle of the letters and the wrong apostrophe.
Did not bookmark any fonts. To bookmark a font, open the details for any of the fonts on AF and flip the Bookmarked status from "no" to "yes"
