Windows 7 network issues after OSX Lion upgrade

Hey so I am kind of a noob at this and I would like some help.
Yesterday I upgraded my iMac from Snow Leopard to Lion. Since I did that I have not experienced any problems opening files from my windows 7 pc on the mac. However I have been having problems doing the opposite (opening mac files on windows 7).

After restarting my pc I say my imac underneath the network category. When I click on this a windows security box comes up and asks for a network password. I am not sure if I am getting this box in an error because everytime I type in the password it says login failure.

So far I haven't changed any settings on both computers.
What am I doing wrong?

Rome.

Having basically the same problem since Lion OS upgrade. Can see my Win 7 Shared folders on the Mac, but cannot see the Mac Shared folders on my Win 7 desktop. Worked perfectly before Lion OS.

Anybody come up with a solution yet?

Hey, after I had restarted the mac I saw it in network on my pc. When I clicked on the mac network it asked me for a network user name and password. Silly me, I kept typing the pc info for this when I should have been typing in the mac info. After that I had no problems sharing files.

My other concern now is formatting an external hard drive so it could be plugged in either to the mac or pc without having to reformat again. I don't think the free-NTFS software is available for OS X Lion yet.