I really like Crunchbang (#!) Waldorf with its Openbox window manager. I like the theme with its dark shades and grays. And, it is light-weight enough for very old boxes and still very functional. And, of course, Crunchbang is backed by Debian Wheezy (stable).
I have installed Crunchbang onto a 10 year old Gateway laptop and a more modern 5 year old Compaq Presario desktop.
My only issue (with Openbox) is that it is difficult to keep the Openbox menu updated with all of the applications I have installed. So, I have written a perl script to read .desktop files and generate Openbox pipe menus (as a replacement to the Debian menu). The perl script generates five menus.
After you download apps-pipe-menu-src.tar.gz (~625 KB), unzip it into your $HOME/Documents folder. Inside the $HOME/Documents/apps-pipe-menu-src folder, a Readme.txt file describes how to install the perl script with examples.
Also, I put together an Introduction to Perl Tutorial for some local high school students. You can grab it here.