MenuetOS can run off of a HD, it can run off of a CD using FD emulation. FD's are dying yes but are they going to disappear off of the face of the earth... not entirely there will still be machines with 3.5in FD drives 10yrs from now same as i still have a Pentium 1 200Mhz Server with a 5.25in FD drive the server is only used as a LAN hub and printer server but it still has a 5.25in FD drive.