I remember Mike from Roland was getting feedback on this. Does anyone know if a sp-404 wave converter program is in the works?? thanks

I guess the 404sx comes with software that can convert 404 samples to reg wav files for the sx- I think- don't have my sx yet.

SX software = sample organizer (which sample goes into which pad)
555 software = wave converter and sample organizer (AFAIK incompatible with 404 compressed files)

I'd guess people tried this already but you might get lucky trying out converters made for other Roland hardware (BR-600 and the like), maybe one of those uses the same compression algorithm.