I believe the setting in Fraps is called "Force lossless RGB capture", what it does is that it records the footage with more color representation but it also takes up a lot more space and puts higher requirements on the transfer speed of your hard drives.
This chart shows the speeds required to use whatever setting you might want to record with.
RAID0 is when you combined 2 or more hard drives in a Raid array but don't use it for redundancy but instead for increased speed, with a RAID0 setup you can almost double the speed of your drives if you use 2 of them. This requires either a Software or hardware to setup, most modern motherboards in the middle class and upwards have support for this.