Re: How can I move my Sims 3 to my new PC

if your games are registered download Origin to your PC 

then login with your Origin account from the desktop shortcut of origin (the origin you download)  with the email and password you use for your  account  my games tab right click the game icon download 

https://www.origin.com/en-us/download

also please take note of the new layout in Origin  http://answers.ea.com/t5/The-Sims-3/FAQ-New-Origin-Layout-for-The-Sims-3-Expansion-Packs/m-p/4641393#U4641393

and last but not least if you still have access to the other computer you can copy your saved games/saved sims lots etc and transfer them over to the new computer otherwise you'll be starting off fresh and if you have any store content you'll need to log into the sims 3 account download your items and install them

http://sims3.crinrict.com/en/2011/03/faq-what-files-should-i-backup.html

edit typo