There is a free and well working open source software that is Microsofr Project alternative.
This is ProjectLibre:
http://www.projectlibre.com/product/projectlibre-open-source
ProjectLibre is leading open source alternative to Microsoft Project.
It has been downloaded over 2,700,000 times in over 200 countries and has won InfoWorld "Best of Open Source" award.
ProjectLibre is compatible with Microsoft Project 2003, 2007 and 2010 files.
You can simply open them on Linux, Mac OS or Windows. ProjectLibre key features: