Figured out my problem
My other post isn't active yet so I'll add my solution here. I couldn't play Din's Curse demo. The mouse was totally invisible. When Steam didn't work, I installed the demo from here but it didn't work, either, maybe because I did not install it to the default directory plus Steam was still installed. I uninstalled and tried the Steam version again. Same problem, so I uninstalled both and started with a clean slate. Using defaults, I installed the demo from this site, changed the Hardware Cursor which solved my mouse problem (that took patience).
I'm already addicted. This is what Diablo should have been.
Great job !!