There should be some RAID configuration utilities that you can run. I'm not sure how Dell has these set up. There is also software RAID and Hardware RAID. RAID 5 is much slower than RAID 0+1 but is more fault tolerant. Also look at the cache on the controllers and see if both are enabled/disabled. As Michael suggested, performance monitor will help in determining what's happening.

You will probably learn more than you'll ever need to know when you're done!

HTH,

Chuck