Hm. Never used the MP3 downloader myself, and Octave has been sufficiently compatible (ie, every bit of code I've encountered/written worked on both) for me to do all the Matlab courses and assignments that I've worked on. I suppose that I should have qualified my original statement -- all the software I cared about as an engineering-physics/computer science student that ran on Linux in the first place runs just fine on Linux 64 bit. (I miss CAD and a good GUI circuit designer, but those were also missing from 32 bit Linux)