You can't compare mirroring and striping on terms of which is better to run for RAID, they are both completely different. Stripe if you want performance, mirror if you want a backup. Or, do what my roommate did...Get 4 hard drives, use 2 for striping and 2 for raid

Check your mobo and make sure it supports 3gbps. If it doesn't, change the jumper to 1.5 so you don't fry the thing!