Get your iBook, and then a copy of AppleWorks. It's kind of the Apple version of Office, and while not as robust (yet)
And will probably never be. AW is no longer being "actively" developed, now Apple is focusing on
iWork.
BTW you should have gotten AW on your wife's iBook, however, it may not have been preinstalled and could still be on her install discs somewhere, although it seems unlikely. If she has upgraded the iBook to Tiger doing an Erase & Install, she will have lost AppleWorks. She may not have noticed that AppleWorks was there until the upgrade, and then obviously it's gone, although she can reinstall it from her original install discs ... otherwise I dont know why AW wasn't there.
To the Original Poster :
I use NeoOffice and it works fine, I am able to read and edit Word files w/out problems. You might want to try it first, and then decide if you still want to buy Office:mac ...
Unless you are a heavy gamer, you will probably get used to OS X very fast (and undoubtedly love it). Helped by these forums, it took me 2 weeks at max. 🙂