Presumably the issue here is about increasing the performance of you computer whilst running Mastercam. Like with any computer system the trick lies with identifying the bottle neck that is causing you machine to slow down. With a CADCAM program I would have thought that fast disk read/write times is great but not the most important factor. Take a look at your machine whilst you are using it, are you constantly opening and saving file every few seconds or so? Liken this to say a file server; in this scenario you might have 100’s maybe 1000’s of people writing files to an array of disks at the same time in which case read/write time is critical. Is your disk light constantly on whilst you are using your machine? This might imply a lack of RAM due to excessive disk caching (this is the paging file on a Windows machine). If you are using Windows NT, 2000 or XP open your task manager check the CPU utilization and amount of free RAM, do they constantly run above 75%? If you have two or more physical disks in your machine try putting the paging file on a separate disk from the OS. I have installed a lot of computer system for CADCAM work. In my experience the most important factors for a fast machine are RAM, CPU, and graphics adapter in that order. Recently I installed twenty Dell MT530 workstations in our drawing office all have plenty of RAM and fast CPU’s, and all have a single SCSI disk an they all cope very well indeed even with large complex models using Solidedge. Look at pre-built workstations from Dell or Compaq etc. none that I know off come with hardware RAID controllers. RAID is primarily a technology for servers providing faster disk readwrite times and fault tolerance. If you still want to use a RAID array in your machine use a hardware RAID setup (as previously mentioned by someone else) but you might fined the cost outweighs the gains.