Is additional backup needed for system with RAID

My computer has an Asus A8N-SLI Deluxe motherboard that has two onboard RAID solutions.  I could not get the Silicon Image drivers to work ( tried both XP and Vista) and had to use the NVIDIA RAID (the operating system is Vista Business).  I have four hard drives that are configured as 1+ 0.  This was also my best choice without going out and purchasing a new hardware solution.  I am running electronic medical records software on MySQL, so obviously backup data is crucial.  I have installed an internal bay hot swappable SATA drive product called HDD-ROM MRA301.  I am going to use this to do a daily back up of my data to keep at least one copy off-site.  My questions are:
1.  With this RAID mirror solution is it also necessary or a good idea for me to have a backup solution for the system otherwise including all my other programs and data not related to the medical record data?
2.  If the opinion is that I should have an additional backup, what program or how to do this backup to completely essentially mirror my system so that I could have a ready immediate fix on a hard drive?
3.  And would this work or when I just have to read build the array?
Thanks.