I act as computer mechanic at a volunteer organization. We've been using Office 97 with XP, but Microsoft has changed the "doc" format in recent MS Office versions so 97 won't do. <longer story skipped here> So I went to the store to buy Office 2007. I read the small print on the box and find that one can use the cheaper "Upgrade" version of Office 2007 if one has MS Works 6 or more recent. That saved us about US$170. Not cheap even after that.
This might explain why Works came with VISTA, No, MS wouldn't go out of their way to save customers some money.