A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Yes, you would need to purchase software to open those files. Microsoft Word 2010 will open those files, see...
http://office.microsoft.com/en-us/try/
OR
You could also try Office Web Apps (never have tried this so not sure if it will work)...
- Login into your windowslive.com account
- Click SkyDrive from the drop sown next to Outlook
- Then upload your document, once done
- Select Files from the left and then
- Select your document and it will open for editing