Raid 0 is a way of making one big drive from 2 or more disks, if one disk goes tits up and you do not have a backup of your data, you are as previously said scr3wed.
Raid 1 will mirror drives, eg 2*200GB disks will give you a resilient 200GB disk in case one fails.
I would recommend cranberries solution, with one small mod
partition primary disk with a 50GB partition and the rest as one disk, OS and apps which have no recoverable configuration only on c:
d: apps which are encapsulated
e: cd
f: data
external disk as a backup.
Raid 0 is a bad idea. I would never use it in my data centre.
hope this helps, now go enjoy the sun