I'm glad you worked it all out, SS.
When I bought my laptop last Thanksgiving I didn't have most of my disks with me because I was at my parent's house. So I looked up how to find them in my old laptop's registry so that I could write them down and download them to my new laptop with Origin.
Of course now I need to uninstall the base game and reinstall off of my disk since I can't run the game using the exe command (without the disk inserted, I mean). Origin has a different version of the Base Game that makes Origin required to play the game. :evil:
I no longer remember where I found the directions for looking it up but Carl's guide has some instructions (with a link for Mac users) here: http://www.carls-sims-3-guide.com/forum/index.php?topic=685.0