Format a floppy with any version of Win9x using the add system files option. The only necessary files on the floppy are io.sys, msdos.sys, and command.com (plus your flash program and the binary BIOS file). If you have a crowded diskette (a win98 startup floppy, for example, fills the diskette with cabinet files, etc.), you can delete everything but the above files. A floppy formatted using win2k (or any other version of NT) will give you the non-system disk error.