last time i sent my mbp in for tech support, tech support had to call me about something so i went ahead and asked them. The tech support guy said that, it was fine to replace both the ram and the hdd, but whenever you send your mac in for support, you should send it in with the factory hd and the factory ram. I've sent it in once before with my own hd, they ended up replacing it with an apple drive, and blamed the problems on a non apple drive. but they didn't void my warrenty