Which is better? RAID 0 or Rapid Storage Technology with SSD

[newlook2]

With Intel's RST one can have a SSD as a cache to the main hard drive. What I'm wondering is it better to have

• two HDin RAID level 0
• one HD and one SSD as cache
• one main HD and two HD in RAID level 0 for cache (is it possible?)

 

[hellokitty[hk]]

I don't think two HDs in RAID 0 for cache is supported, either way, it's not going to be fast.
A good SSD will beat out the RAID HDDs anyway.