This is the oxygen theme for xfwm4. It's not perfect, never will be, since I probably won't be updating it. All the buttons and borders are copied straight from the theme by kimmik (http://www.xfce-look.org/content/show.php/KDE4+Oxygen+new+port+for+GNOME?content=86653) and some are modified a bit.
For the theme for the ui, follow the previous link. The ui works with gtk 2.x.
For icons, get the oxygen-refit theme (http://www.gnome-look.org/content/show.php/Oxygen+Refit+2?content=79756).
Extract the folder and move it to /usr/share/themes.