RAID 0 will always increase the chance of data loss, not lessen it.
I would suggest RAID1 for the system drive, because it will give faster read performance, but still the same write performance of a single drive (generally you do not write much to the system drive except for installing programs... which is generally limited by your CD/download speed anyways. If you are using this drive for rendering then it could be OK to do a RAID0, but be sure to make a backup image periodically in the event of a drive failure.
For the storage I would suggest RAID 5 or 10, but absolutely not 0 as this is where all important files live.
5 is a little slower than 10, and takes a CPU hit to operate, but only looses a single drive of space for redundancy (capacity is n-1).
10 gives a little more performance and less CPU overhead than 5, but will always be 50% of the total drive capacity (capacity is n/2).
I love OCZ and have their SSDs in my and my wife's rig, but these are throw-away drives, and not suggested when reliability is of concern. I would stick with Intel or Crucial M4 drives for this type of build.
Oh, and I have no idea if the mobo will have the capability to handle 2 seperate raids with a total of 6 drives.
Also, Stick with SATA 3 drives. While in theory SATA3 drives would overwhelm the SATA2 controller, the real world is a different place. Uncompressable data only moves at ~150-200MB/s on the fastest of SATA3 drives, which is still faster than their SATA2 counterparts, but still slower than the max throughput of the SATA2 interface. Compressable data will hit a bottleneck, but with this kind of build/budget it is better to hit a limit than to have unused potential.
If your client asked for raid, and did not specify what type, then perhaps he does not understand the purpose for raid. I suspect that the interest is in fault tolerance and not sequential speed. I think this should be clarified.
What is the primary intended use for this pc?
The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years. SSD's are similar.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, fire, theft, raid controller failure, etc.
For that, you need external backup. If you have external backup, and can tolerate some recovery time, you do not need raid-1
I think I would just use large Intel 520 drives, they come in sizes up to 480gb. Even the 320 series would be good, they come in 600gb size.
Use one for the os and apps. Attach the rest individually as separate drives. If a single large virtual mage is needed, that can be done with software spanning or concatination.
If raid, of whatever type is a necessity, then consider a raid card with a discrete raid processor.
It will have more performance and reliability features than motherboard raid will.