There once was a supposedly portable edition (of the full one, not the SE) that turned out not to be truly portable — by any correct understanding of the term. It went onto a flash drive, but was not self-contained, putting lots of required files onto your computer’s hard drive, including stuff into the Registry. That version probably came from here, some years back. I tried it, ended up chucking it. Should it ever return, but this time in a truly self-contained, portable format, I would be game to take another look.