For everything I do, I have really grown to be a big fan of online word processors
Its almost like Email, in a way... if you have a Google account, I strongly recommend you check out
www.docs.google.com and see how it is. Right now, they only have Documents (like MS Word), Spreadsheets (like Excel) and the newest feature is Presentation (PowerPoint)
I dont think you see ads at all when you are creating/editing documents (I have AdblockPlus, so I don't know) which is convenient.