The Sims 3 Question

I just bought The Sims 3. I was wondering what was ABSOLUTELY required to play the Sims. Because I could definitely live with a slow Sims. Well, not really, but I'm really depressed. I went to Can You Run It.com and it said I couldn't. There are three things I failed on: RAM, Video Card RAM, and Pixel Shader 2.0 (I'm going to get it soon hopefully) Which one of those absolutely requires it when you install The Sims 3? I'm sure RAM is just to speed it up. I'm not sure about Video Card RAM and Pixel Shader 2.0 yet though. I was wondering if you guys knew any sites with free Video Card RAM and free RAM booster. Thanks!