Question: You want to write some Word documents in the new docx format but there’s no Office 2007 on your computer.
Solution: This problem can be easily solved using Buzzword, the online word processor from Adobe.
Either create a new document from scratch or upload an existing Word 2003 file and Buzzword will convert that to docx which is the default file format of Word 2007.
Like Zoho Writer or Google Docs, Buzzword can also export Word docs to HTML format.
Related: Open docx Documents Without Word 2007