I have an Early 2008 Mac Pro (3,1) 2x 2.8 Ghz. I am currently using a 240 GB Mercury Accelsior PCI SSD as my boot drive (with OS X & applications) and triple RAID0 (with 3 750 GB Western Digital drives) as my Data drive (with docs, pictures, video, music). I have 18 GB of RAM. I do a lot of photography work so I am looking to optimize performance in Lightroom and Photoshop. I also want a little more space on my Data drive. I'm considering two options: 1) A single Hitachi 4 TB (7K400). 2) A RAID0 with 2 x 2 TB Hitachi (7K300) drives. Which would be faster? I'm pretty sure it would be the RAID, but I wanted to double check. Any other ideas for increasing Photoshop/Lightroom performance?