For you iPad, iWorks app suite , Apple is making it incredibly easy to view, edit and transfer Microsoft Office files between your iPad and either a Mac or a PC. You have to purchase each of the apps individually, which is a small price to pay for the convenience of viewing and editing important documents anywhere at anytime. The Pages app is compatible with Microsoft Word, the Numbers app is compatible with Microsoft Excel and the Keynote app is compatible with Microsoft PowerPoint. It’s a great way to finish a last-minute homework assignment or fine-tune a big presentation.
Update: The iWorks apps are now free from iOS 7 onwards depending on your iPad / iPhone model.
Select your iPad from beneath the Devices section in the navigation pane on the left. Select the "Apps" tab and move down the screen until you see "File Sharing."
Disconnect the iPad from your computer, select the iWork app that corresponds with the file you just imported and select "My Document," "Spreadsheets" or "Presentations." Press the folder icon in the upper-left corner of your screen. Select the Microsoft Office file that you wish to import.
Select "Export" in the dialogue box that appears. In the next dialogue box that pops up, select the corresponding Microsoft Office format to export the file in.