Well I've done this twice on my laptop.
I bought a SSD drive with a Kit. The Kit came with a USB drive case and with cloning software. I put the new SSD drive into the drive case and booted with the cloning software. Once it finsihed cloning I took the new drive out of the external enclosure and I removed the old drive with the new one. I did move the old boot drive to the second slot. I since got a bigger SSD drive and I cloned the first SSD on to the new bigger one. I also just recently went from 750 GB on the second drive to 1 TB so I did it again. For some reason when I cloned the secondary drive it made a complete clone and made the partitian 750 eventhough the drive was 1 TB. So I downloaded a free partitian manager application and increaded the partitian size from 750 GB to 1TB (1000gb). I didn't have to do that with the SSD I cloned.