So is it worth the trouble to set up a RAID array?
Trouble? no trouble, it's actually pretty easy to do. There is a bit of cost though. If you already have the hard drives, and only need a raid controller, I say go for it. If however you don't have any of the required hardware, and maybe don't *need* the extra hard drive speed, then maybe you shouldn't invest in the hardware.
I setup RAID 0 in my gaming rig to help with the load time of games, and copying/moving files. I do a bit of DVD stuff as well. I think the extra speed has helped. It's hard to say exactly how much it has improved though. I don't think boot time or general Windows application load time has improved much though.
My setup:
Promise FastTrak100 TX2 ATA100 raid controller.
2 x Seagate 7200.7 80gb 2mb cache ATA100 hard drives.
I know there are faster drives, but I chose these because they are fast, yet also quiet. There is an 8mb version, but it is quite a bit more money right now than the 2mb version...