[URL=http://www.pcworld.com/news/article/0,aid,108231,00.asp]PCWorld[/URL] puts it into simple terms, they put a RAID setup in the test bench against single drives and see what the performance differences can get like.

[COLOR=royalblue]Once reserved for servers and high-end workstations, RAID technology for linking multiple hard drives is gaining favor with PC users looking to improve performance affordably. Tests by PC World show they're on to something: Two RAID-connected drives completed some tasks in 40 percent less time than one drive of the same type.[/COLOR]