HA,
BY default Samba puts WIndows shares in the workgroup workgroup. A Windows 7 rig in the same workgroup should see the share. Homegroup means nothing to Samba, in Windows 7 networking you have to get the machine into the workgroup workgroup.
One problem I had with Samba was that after an ubuntu update, samba stopped working. I had to remove it and reinstall it. I recommend you do that. First update ubuntu. From the terminal window (Applications/Accessories) enter:
sudo apt-get update
then
sudo apt-get dist-upgrade
Navigate (places) to the Folding directory and turn off file sharing on the folder (right click, sharing options).
Open a terminal window and remove samba:
sudo apt-get remove samba
answer yes to proceed.
then reinstall it:
sudo apt-get install samba
Now navigate to the folding directory and right click on it, sharing options, check share, let others change my files and allow guest access. It should work after that.