This is one of the reason why The T-Series Thinkpads rock! You have the ability to host Triple drives!
In addition to the standard internal, you can use an ultra-bay to host a second drive. Then you can add an mSATA SSD for a third drive.
I just upgraded my mSATA on my Thinkpad T420 from a Crucial M4 128GB to a Crucial M4 256GB. I have dual SSDs and a 750GB 7200 rpm data drive! One SSD for my OS and a second SSD for my Virtual Machines. With 16GB of RAM, this baby flies. Take that Mr. Ultrabook!