Kingsoft Office 2012 is almost a replica of Microsoft Office 2003, and it's only about 65 MB big. It has a writer, spreadsheet program, and a presentation program. It's like the chinese version of Office, and it's free. Though it opens docx formats, however, unfortunately, it doesn't have a default option to save docx files. Check it out here:
http://www.kingsoftstore.com/office-suite-free.html.
Once installed, go to Tools>Options>General and Save (tab)
In Measurement units, click on Inches, and uncheck "Use Character Units"
In save, click on your preferred save format (generally .doc)
Press OK, and now you have an exact lookalike to Office 2003!