Pretty sure there were reports early on that Sims wasn't running happily in the D drive. You might want to search the Forum.
Copy over your Origin Games folder to the directory you want it in, then uninstall and reinstall Origin to that drive. It should detect the install and you don't have to redownload. I don't see why it wouldn't - I had Dragon Age II installed from disc long before I activated it on Origin, and it found it in a totally different directory.