The point of RAID isn't necessarily performance, thats just a side effect of everything other than a striped array.

RAID1 as a primary logical disk and RAID0 as a secondary logical disk. Throw the important stuff of the primary, and the performance and non critical stuff on the secondary. Yummy.

Also, when you have to move GIGS of files between disks or into photoshop/whathaveyou you will notice a big difference. I certainly do

If all you do is play Q3 then I doubt you're going to benefit as much. Unless you unpack your pk3's, then you get read speed limited instead of cpu when loading. Lousy ZIP compression

http://www.trickingq3.com/misc/photoshop/forum_posted/performance.jpg