I'm configuring a mac pro right now and have 2 questions: 1. If I build a machine with 2 internal hard drives can I use one of them for my system drive and the other one for Time Machine? I wasn't sure if Time Machine could only use external drives. 2. What is faster 3-4 nvidia geforce 7300gt cards or 1 ati 1900xt card - basically my question is do the nvidia cards stack for performance or is the purpose of getting many of them only for multiple display support? I don't play any games but want to keep open the option to play starcraft 2 on it as I loved the original from my childhood and would love to try out the new edition.