How much RAM do I need to run Spore smoothly?

I'm currently using a computer that has 446 MBs of RAM (Slow, I know), and I'm goig to get a laptop for christmas, and I'm going to be buying it mainly for games and various programs, and I was wondering what a good RAM amount would be for Spore to run at its highest quality? I would also appreciate an answer for how much RAM I'd need to run GTA IV for PC smoothly