Here's my situation: I had a black MacBook (2.16GHz CoreDuo) with 3Gb of DDR2 667MHz RAM. My brother got (for Christmas) the new Unibody MacBook (2.26Ghz Core2Duo) with 2Gb of DDR3 1066MHz RAM. Since I am going to college next year, I asked him if we could switch computers since I didn't think mine could hold up to a year of campus abuse (it has served me well daily for 3 years). He graciously helped me out. I switched the HDDs in the computers so that my HDD (from the black one) was now in the new white one, and visa versa. Immediately I noticed that on the new white MacBook when several apps were open, the computer slowed down significantly. I am wondering whether or not I can switch the RAM between the computers as well (so that the 3Gb of DDR2 667MHz is now in the white Unibody MacBook and visa versa). Will the white MacBook be faster? And can the black MacBook (with a CoreDuo processor) handle the DDR3? Suggestions?