I've been mooching about on this and other forums for a few weeks and am now the proud owner of a Mac Pro. I am getting myself a little confused around what disks to buy however I want to buy them tonight / tomorrow morning as I need them in place on Friday morning for a demonstration - so sorry for the pressure. I will be using the machine to run both Mac OS and Windows (xp or vista 64 to take advantage of all that lovely RAM / processor power). The machine will be mainly used for office work and video editing. I understand that having a large drive for backups is a good idea so that's one slot taken up with a 1TB drive, so I assume this leaves me with 3 drives to play with (unless putting a partition on this drive is a good idea??) I've picked up that RAID 0 can be a good idea as long as your backups are good however I'm not sure what to RAID and what is a good thing to put on the RAID! As such 1. What is the best segmentation of OS, Apps and Data?: - i. Three normal disks - ii. OS and Apps on RAID 0 with Data on single - iii. OS on single with Apps and Data on RAID 0 - iv. OS and Data on RAID and Apps on single (I really am not expecting this one to win - I'm just including for completeness!) 2. How much disk space should one allow for dual book OS (Mac and Windows)? 3. Is there an amount of "headroom" which is sensible to allow on a disk - i.e. if I look on my laptop I have in total 60GB used for OS, Apps and Data however I am not doing any video work on the laptop. 4. Are there different charateristics I should be looking for in Boot / OS disks, apps disks and data disks - the review by bare feats (http://www.barefeats.com/quad08.html ) is very interesting if a little out of date. 5. Can you fit more drives in than 4? I ask as I'm sure I heard of someone putting one in place of the other optical drive however I might have been dreaming! 6. Is is a good idea to boot off a RIAD 0 pair? 7. From reading around it seems that Windows can't see any disks in a RAID and hence I guess I need to put Windows and the data it needs to see on a non RAID, I assume it is still a good idea to have the Windows data on a seperate partition to the OS and Apps or is a seperate drive a good idea? Many thanks Miles PS an alternative to the wacky idea of installing more disks internally would appear to be to install the backup disk externally as suggested by the following extract from http://www.barefeats.com/hard94.html : For this test session, we installed all four drives inside our 8-core Mac Pro. In the past, SATA drives have performed well connected externally to 3G SATA host adapters. However, they sometimes "stumble" when installed internally to the Mac Pro using the built-in SATA controller. We can assure you that these drives perform as good or better than you see below if you choose to install them in an external enclosure and connect them to a 3G SATA host adapter.