I've been tearing my hair out about this too. Just got an iMac Flat Panel, and I can't see my windows shared printers any more.

I say any more because I USED TO SEE THEM! Then I re-installed the OS and no more! Instead I have to set them up manually by holding the option key and choosing advanced from the menu.

Anyone got an idea how to get them to appear?

Also, how do I print to a windows shared printer that is a downloaded driver, not an OS supplied one? The printer doesn't appear in the list (by company name) and if I choose "other" I get a file dialog that looks for some file - where should I point it?

If I connect the printer locally to USB (It's a Samsung ML-1510 by the way) then it works fine and the driver just seems to choose itself!

You might want to check that the Network Neighborhood is set correctly in the Directory Access utility (SMB needs to match your Windows, I think).
Still trying to get this to work, it should not be this hard.