I won't pretend I know the deep meanings of the following advices (like about WINS), they may not be the best options, and I'm not talking from knowing the inner workings. It's just from some experience on "try to see what happens" and some knowledge.
That's most likely a windows issue, unless you have tweaked your MBP. It comes as default prepared to see any windows network, and even linux.
The Locations are just presets for each place you go, if you wish to have many different configurations. I personally just leave it always on Automatic.
But regardless, try removing any WINS configuration you've set, it's not needed. It's supposed to accelerate things, but you most likely don't have a WINS server anyway and even if you did, in such a small network, you wouldn't need that kinda of performance gain.
As for the windows side, maybe it's because you've set users and permissions on it and forgot to allow some public access or broadcast. "smb://uname:pass" is quite unusual for printing in a Home Network or even most offices, so I'd guess you've tweaked quite a bit.