You need to get software called Quick Office Premier.
It costs $50
If you need compatability with Office 2007, you have to get Quick Office Premier 5.0, which costs $70. I'm not sure, but I think 5.0 is the only version that can print.
Here's the Quick Office website
Quickoffice Premier for S60 3rd Edition
I'm not sure, but I think the N73 comes with a free Quick Office version that can view Word files but cannot edit.