Wiki compares project management software
Source Forge download project management software
accroding to Source Forge:
"ProjectLibre is an open source alternative to Microsoft Project. We have a community site as well at http://www.projectlibre.org It has been downloaded in 194 countries the first month of release and was just voted Sourceforge's "Project of the Month" ProjectLibre is compatible with Microsoft Project 2003, 2007 and 2010 files. You can simply open them on Linux, Mac OS or Windows."