Microsoft Digital Image 9 is ancient and incompatible with recent versions of Windows. Even the most recent version (Digital Image 2006) was only compatible with XP (unless you bought the 'anniversary edition', which could also run under Vista).
It's unlikely that you'll find any version of Microsoft Digital Image anywhere. Additionally, any free version would almost certainly be riddled with malware.
If you're simply looking to enhance your photos (and don't want the steep learning curve that GIMP requires), look no further than Serif PhotoPlus Starter Edition:
http://www.serif.com/free-photo-editing-software/?MC=FSSPHOTOPLUS
It's outstanding software, easy to use and completely free.