From what I read on other Sims forums, Sims won't run so smoothly on a MacBook. The base game alone should be fine, but the performance would deteriorate with every expansion pack installed.

I used to play Sims on a laptop that had the GMA950. Several graphic options were unavailable, and after extended game play, the textures would go blurry despite my settings set to the highest. I experienced a fair bit of lag too on big lots, or lots that had a lot of Sims on them. (If it helps, I had 1.5GB of RAM on that laptop.)

Another brand of laptop, I presume?