Using mSATA SSD as Cache AND OS drive?

Hi,

Here is my current system that I am planning to build:

Core i7-3770K
Gigabyte Z77-D3H
16 GB Kingston HyperX DDR3 1600
Gigabyte Geforce GTX 660Ti
1.5 TB WD 5400 RPM HD (This is from my old PC)
500 GB WD 5400 RPM HD (This is from my old PC)

I would like to add an SSD to improve the performance of my PC with every-day tasks.

The one thing I noticed about the Z77 board that I'm using is that it includes an mSATA slot which can be used for caching (Intel SRT)

Now my question is... if I buy a 256 GB mSATA SSD drive, can I partition it into 64 GB for the cache to speed up my HDD access times and leave the remaining 192 GB for OS and program installation?

Or would it be better to simply buy a 256 GB SATA III drive?

The price differential between the mSATA and SATA is not a concern (it's only ~$10 apart)

http://www.newegg.ca/Product/Product.aspx?Item=N82E1682... ($199)
http://www.newegg.ca/Product/Product.aspx?Item=N82E1682... ($189)

So basically, is this possible, and if so, how would the performance for these two setups comparatively?

Thanks