I do not need a project manager being projectless, but know that GNOME has
its own called ironically enough, Planner. You might want to give it a try.
Of course as you might expect, KDE has its own called Kplato. And there is
java based Microsoft Project replacement called Openproj.
http://openproj.org/openproj

See also:
www.linuxlinks.com/.../ProjectManagement.html