I don't think hardware is going to be a problem with Sims 1. The game itself has lower requirements than Windows 7, so if the guy can run Windows 7 with ease in the first place he will most likely have enough machine to run the game too.
I would not run in any compatibility mode unless I know it's 100% needed or have a strong reason to do so. Just my opinion. I like to run things in the most "natural" way as possible.