If you need or could take advantage of some of the new features or improvements of the 2007 version, then you should consider upgrading, otherwise, you could continue using your current version.
Here’s some information of the new features or improvements in 2007:
<a href=”http://www.microsoft.com/officebusiness/products/compare-suites.aspx”>Microsoft Office Professional Plus 2007 Version Comparison</a>
And here is a document explaining how to install the compatibility pack, which will allow you to open Office 2007 documents (such as docx files) in previous versions of Office.
<a href=”http://office.microsoft.com/en-us/word/HA100444731033.aspx”>Open a Word 2007 document in an earlier version of Word</a>