Next time when you receive a spreadsheet from an unknown source and are afraid of opening it, fear not. If you are using GMail then you can just simply open that document in Google Spreadsheet and not worry about viruses at all. Google Spreadsheet opens the documents in the browser window itself. Once you have verified the authenticity or the usefulness of the document, you can then download it. For MS-Word document attachments you can just view them as HTML through GMail.
I am not sure whether other email providers like Yahoo, AOL, Hotmail have this facility or not.
Thougth, I’d share this tip with you.