[ubuntu] How to get Ubuntu to see Windows machines???

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http://ubuntuforums.org – I have 4 machines set up. 2 are running Ubuntu 12.04 LTS, 1 is running Windows 2003 server, and 1 is dual booting WinXP and Win7. 1 of the Ubuntu machines is configured to share out 2 disk volumes ("Data" and "DiskImages". My windows machines can see these shares. My other Ubuntu machine cannot. Neither of the Ubuntu machines can see any other machine on my local network (although i can sucessfully ping any of them from my shared out Ubuntu machine. I want to get it where all of my machines can see eachother and move files back and forth, as the ubuntu machines are going to (Hardware)