"Seeking Assistance: EA Launcher Prevents Game Launch Despite Valid Key"

ss658a6bbq0v​  I would suggest borrowing one first, if you have a friend or family member who has an external disc drive.  I've heard stories about the occasional drive not working with Sims 3 discs, although it's rare.  If the one you borrow works, you could buy it off its current owner, or buy the same model, without worrying about whether it'll work.  There's also a way to get around using the disc each time you play if you don't want to damage the discs.

Anyway, most of this is a moot point until you're actually installing.  The one important step to do before you start is a clean uninstall of Sims 3, which you can do as described here:

[Read First] Running Sims 3 in Windows | EA Forums - 8323446