Bundling two separate pdf files in a single pdf file

As an academician, one of the most needed software is a software that can convert a Office document into a pdf format.Fortunately, the Microsoft Office 2007 that I am currently using has such option by clicking "Safe as" and choosing pdf from the top-down menu option.But the other equally needed program that I need is a software that can bind two separate pdf files into a single pdf.This would be