I would backup everything thats of any value to you as quick as you can, then remove the faulty drive. Because it is striped you lose the data on both drives. One thing to take note of is when you get a new drive it ideally needs to be the same size as the existing drive and the same speed.
If you didn't use over 500GB on your original setup I would stick another 500GB drive in and set it to RAID 1 (Mirror) instead. That way everytime the data is written to the first drive it is also written to the second drive so you would always have an instant back up.
If it was me personally, I would get a 120GB SSD Drive, stick this in as the master drive and put Windows, Lightroom, Photoshop, etc on it and then put the working 500GB drive in the 2nd slot and use this for all your data. The speed difference between a normal hard drive and an SSD is very noticeable, my laptop boots in 6 seconds from cold to the desktop.
I would then get an external hard drive as well and use that to do regular backups of everything just to be on the safe side.
I put loads of customers on to SSD's when I had my computer repair shop and they were all chuffed to bits at the speed increase.
If you need any further help feel free to PM me.
Chris