I need an mSATA as close as good to the samsung 840 pro 256 as possible!?!?

You will only be able to create a software (Windows) RAID-0 array with a mSATA SSD and a SATA SSD.
You won't be able to create a firmware (motherboard) RAID-0 array or a hardware (PCIe controller card) RAID-0 array.

Probably best if you just used the 2 drives separately.