Why not use icons from the tango project?
There's also the nuvola icon theme, which, conveniently, is already LGPL: http://www.icon-king.com/projects/nuvola/ --Juan
I believe windows contains some generic icons build into shell32 and some other dlls but theme files can override them. If that is indeed the case we could just ship some wine icon themes (or use free win32 themes). Stock icons from e.g. pango or so would be nice for the generic ones.
Roderick