Opening an Office 2007 Document with Office XP

I recently received a Word 2007 document with a .docx extension and I still had Office XP. My concern was that I was unable to open the document. My thought was - Wow, Microsoft didn't think this through. However - they did. There is a compatibilty pack that you may download and run to open the document. As well, the current version of Open Office will allow you to open Office 2007 Documents. This can be especially difficult for students who received .docx documents from there professors and have older versions of office or open office.