This first link is a nifty chart that shows you how well your Graphics card would fare with certain expansions. Your card falls into the "Maybe" category with Showtime. http://simswiki.info/wiki.php?title=Game_Help:TS3_System_Requirements
This second link is a little more in-depth with Showtime requirements, which shows that you fall a tad short when it comes to processing power, but you seem to be okay on everything else.
http://help.ea.com/en/article/what-are-the-system-requirements-for-the-sims-3-showtime/
As far as the Code 12 error goes, are you running Windows 7 32-bit or 64-bit?
@CitrusViking the OP mentioned a 64-bit system, if I read it right 😕mileywink:
I hope that, by "I don't have time for research" you mean that you don't mean you don't have time for reading posts on the issue, because otherwise, you're going to be stuck.
The last two are just possible maybes that you might want to look at. If none of them help you, could you post your dxdiag please? http://answers.ea.com/t5/The-Sims-3/HOW-TO-DxDiag-for-Sims-3-PC-Only/m-p/1049584/thread-id/47181
