I have 512mb's of old PC5300 RAM from my old iBook and was wondering if it would give any significant performance increase if I swapped it with the macbook's current 256 stick. Remember this would make me have unmatched sticks in the macbook.
It won't work. The RAM in the MacBook is different from the RAM that the iBooks use. You won't be able to swap the two. If you'd like to upgrade your ram, I recommend Data Memory Systems. They've got good prices, and guarantee their RAM.