You aren't the only one experiencing this problem. I did a little research on this. MS Works 9 was the edition that was recommended for Vista. Some Works 8 users have been able to run it in Vista (those using the 8.5 edition or later seem to be getting fewer error messages - but not all); but it seems most users are getting the error message you got.
You might want to try using the free office suite LibreOffice (formerly known as OpenOffice). It will open your Works files. It will not save files in that format, but you will be able to save them in MS Office formats, or the default Open Document format. LibreOffice is available from www.libreoffice.org
If you are looking for something with a calendar, try Windows Live Essentials email program Windows Live Mail. It has a calendar available as part of the program (similar to Outlook). http://explore.live.com/windows-live-essentials.
Edited by jfruch1, 11 January 2012 - 11:23 AM.