Snowflake,

Change your subnet mask to read: 255.0.0.0 on all of your machines and reboot to take effect on the windows machines. As for the linux machines, just do ifdown eth1 and then ifconfig eth1 subnet 255.0.0.0 <enter> and ifup eth1 and you're good to go. If you're not comfortable using the command line, then netcardconfig (GUI) alone should do it for you.