Supposing you don't want to violate anybody's copyright - nevermind that Microsoft Office has gotten harder to steal these days with their Steam-like digital validation stuff - but you still want cheap Office software? My last copy of Microsoft Word, which I found on Froogle, was only $30 or something, but it turned out it was an illegally sold OEM copy. So I didn't want to go that route again.
And then someone suggested OpenOffice. I tried it many years ago, back when open source was the big craze, and it sucked; it was barely functional. I tried it again recently, and, hot damn! It's like a complete office software suite for free! Although it saves documents in its own internal formats, you can still export to Word and Excel, to share your stuff with the rest of the money-paying world. Every now and then there's some kind of glitch - weird things like using drop caps made it export to Word incorrectly, stuff like that - but it does almost everything I want to do.
Excpet you can't share spreadsheets the way you can with Excel. Since Joel Spolsky's scheduling system is still my favorite way to schedule projects - although it sure has its problems - I'm not sure I could roll out OpenOffice instead of Microsoft at a game development studio. Sure would be nice to lose that $500 per person capital expense, though.