I keep getting this error message whenever I try to run CS: "This application is not compatible with the installed operating system. Please upgrade to Windows 98SE, Windows 2000 or better." I tried running as administrator, running in compatibility mode, updating the Graphics Rules and Video Card files (backing up the originals of course), trying out every answer I could find online but it just won't work. (This doesn't make sense to me considering The Sims 2 installed through CD runs just fine, and that came out a few years before CS.) Am I out of luck?

You may need a no-CD file, unfortunately.