I already have a RAID0 setup and want to add a SSD as an OS/application drive, but I don't want to loose the data on my current harddrives. Many people say to unplug all other harddrives and install the OS on the SSD and then plug the harddrives back in. Will my motherboard recognize my harddrives as a RAID system when I plug them back in and pick up where they left off, or will I have to reset-up the RAID array and loose all of my data?
You should be fine just unplugging the drives power cables to install to the SSD. When you are done and reconnect the power, your RAID controller on the motherboard will see the drives just fine. Make sure you install your RAID management software/application on your SSD first.