Yep they can although you have to keep in mind that the bootloader of windows 9x cannot boot up linux (or any other os besides win 9x) so you have to use LILO or Grub also watch it when you partition your hard drive's (easiest way is to just have to hard disks and use a disk per os) if you make a mistake you can well delete your already running os and delete data on the disk.
Regards

Bad_Karma