Add on at least 512mb to bring yourself to 768mb. You'll be much happier now, and in the future. It's about $50 on newegg.com

If you can afford a 1gb ram, It's about $100-130 and you will notice a huge improvement in performance and speed with that.

I'm running on a PowerBook with 1gb, and going from 512 to 1gb definitely made a huge improvement.