For office 2003 users
If you have Office 2003, Download and install the Sun ODF Plugin should just work.
For office 2007 users
1. First you need to Install Service Pack 1 for Office 2007.
2. Install Sun ODF Plugin for Microsoft Office.
3. Open ODT document via File > Open, or by double-clicking the ODT file and when prompted for the application to open it with, choose Word.
If you don’t have administrator privileges to install software, you can try an online converter such as Zamzar or Media Convert. You can also upload ODT documents to Google Docs or Zoho Writer.
If you want to open ODT documents locally but want to stay away from MS Office, try the lightweight, cross-platform Abiword or the full-blown suite of OpenOffice.org.