Hello All, I have a Mac Pro 2.66 on the way (hasn't arrived yet). For the cost benefit, I chose to get a second 500 GB hard drive from OWC instead of getting a larger drive from Apple with the computer. I could get a second drive cheaper than I could upgrade to a 500 GB drive. So, basically for the same amount of money, I'll have 750 GB of space instead of 500 GB. Anyway, I am unsure of which slot would be the best to locate the second drive. I am looking at this purely from a performance perspective. I know that with PC's using ATA drives, I would always want to have them on separate channels. This was to eliminate the bottleneck (even if only theoretical) that could be caused by utilizing two drives on the same channel simultaneously (it was particularly important for burning DVD's a few years back). For example, I would have placed one drive on Primary Master, and the other on Secondary Master. This would provide the least potential for bottlenecks. Of course, if I had a CD-Writer or DVD-Writer, then I would ideally place it as Secondary Master and put both hard drives on the Primary Bus as Master and Slave to minimize potential for Buffer Under-runs when burning discs. So, that brings me to the Mac Pro. It uses SATA. I am unsure as to whether there are separated channels and buses and Master and Slave arrangements with SATA. So, since the machine will come with a DVD-Writer (SuperDrive) - Which I assume will be on a standard PATA connector - and also a single SATA hard drive, where should I ideally locate the second hard drive I install. Again, I am aware that I can simply plug it into any of the slots. But, which slot would be on a separate bus from the existing drive? Or, does it even work that way with the Mac Pro. Again, looking at this from a pure performance standpoint, and looking to eliminate the potential for bottlenecks if both drives are being accessed at the same time. Basically, to minimize potential competition for the bus. I'll look forward to your input and suggestions. Thank you.