windows 7 - Faster SSD performance as cache drive or regular boot drive?

I have the choice of setting up a system:

• with two SSD Drives in RAID 1 mode as my boot drive for Windows 7 64-bit, with the Program Files and User folders moved to a second regular hard drive, also configured using RAID 1.

or…

• set up a single SSD Drive (120 GB or 256 GB) as a cache drive using Intel Rapid Storage Technology combined with two normal hard drives configured as RAID 1.

Which setup would have the faster hard drive performance over the life of the computer, and why?