Is the installation showing an error message of some kind? Could it be your download is corrupt?
Just remember the minimum requirements for Project Pro have increased, and you need at Least Windows 7 with .NET 3.5 and IE8.
The only reason you might need the other parts of office is for the Visual Reports part which require Excel and Visio.
James Boman - http://www.boman.biz Software Consultant for IPMO - http://www.ipmo.com.au