Making sure I don't fry with a 12V power supply

Coincidentally, is there any way to attach a heatsink to the Duemilanove's Voltage Regulator? It gets a bit hot sometimes, and I'm curious if it's possible to cool it down a bit without major modifications.

I dunno, is it soldered to the board, is it like the one on the homepage where the tab has not been cut off and there is a mounting hole?

if no its not soldered and yes it does have the mounting tab, then yes you can slide one of those U shaped heatsink's under it and bolt it to the board ... its what I have on mine and eventho it is no where near what I would like to have, it does help