There is a handy open source program to organize all your bibliography in bibtex. Bibtex is a open source code which is mainly used for managing bibliography for latex-documents, but which can also be used for MS Word.

The program can be downloaded here: http://jabref.sourceforge.net/
Screenshots are available here: http://jabref.sourceforge.net/screenshots.php

One nice feature is that you can easily combine different bibtex-files. Just open one of your .bib-files, go to file–>import into current database and select the file you would like to import. Don’t worry about duplicates in your new database, they are detected automatically.