A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
In the Save as window (Office button > Save as), there is a Tools button at the bottom. Click it and go to Web Options. On the Encoding tab you can pick Unicode (UTF-8) from the 'Save this document as' drop-down menu.
Alternatively, you can upload the file to Google Docs and redownload as CSV with UTF-8 formatting.
There is also an addin, which I haven't tested myself, that can save Unicode CSV files.
http://jaimonmathew.wordpress.com/2011/08/23/excel\_addin\_to\_work\_with\_unicode\_csv/