I never recommend a raid 0 for storage, this is called a stripped array in which you will get more space and better performance, however if 1 single drive fails you will likely lose all of your data on both drives. The data is split between the 2 drives so if 1 drive fails you have fragments of data left on the other.
Raid 1 is a mirrored array (recommended but your total space with 2*500GB hard drives would be 500GB not 1TB), this means that both drives contain the same data. If 1 drive fails you have a very good chance of recovering data from the other working drive or adding a new drive and rebuilding. Both drives are clones of eachother so you do not double the space with 2 drives.
You would likely need to reload windows to make a stripped array, a mirrored array may be possible but I usually reload before building any array.
If you only have the budget for 2 hard drives total, just add a second drive for storage do not stripe it in raid 0. This way if 1 drive fails you do not lose everything.
If you have a bigger budget you might go with a raid 5 or raid 10. You can read about the most common raid types here: http://www.thegeekstuff.com/2010/08/raid-levels-tutorial/
Edited by zingo156, 25 February 2014 - 08:38 AM.