Choose a hard drive today

I'm not a major geek, that's why I'm here. I need a high performance computer
but can't possibly afford it. My old piece of junk is failing fast. Therefore,
I need to order a computer today! I'm going to get an HP and the choices are so limited Argggggghhh.
MY QUESTIONS:
1) Which is better or is there any significant difference?
320GB RAID 0 (2x160GB SATA HDDS)
OR
400GB 7200 rpm SATA hard drive

2) Are RAID 0 known to fail often? Is it a less safe bet than the SATA?

I use my computer mostly for Photoshop, downloading video, making DVDs - heavy on multimedia.
Thanks for any advice!

 

Thank you for the information and brilliant insight. I am overwhelmed by the responses.

 

We volunteer our time to try to help people out. Please be patient while you wait for responses.

I think you can get away with non-RAID single drives setup. 400GB 7200 rpm SATA hard drive. Back up your files to DVDs.

 

If you can get more space on a non-RAID setup do that.

2 hard drives just gives you 2 chances to fail and if you RAID 0 it then you lose the data on both anyway.