I am at my wits end!!

soccerstar0009​  The "unable to identify hardware" error hasn't typically been related to the graphics card; that's the "unrecognized video card" error.  One theory I've seen is that the hardware error references a sound device, the details of which aren't reported in the DeviceConfig file, so it's impossible to confirm the normal way.  What is clear though is that you can ignore it as long as you don't see other issues.

And yes, you can move your saves to the new Windows account.  Anything you drop in C:\Users\Public would be accessible from any account.  I would only transfer individual files and subfolders though, not the entire Sims 3 folder, since something inside might be corrupt.  Move only the data you want to preserve, like saves, rather than everything inside the old folder, and keep the new folder's existing subfolders where appropriate.  For example, keep the new Saves folder and place your old saves inside that one by one.