Well the thing is that since SSD'S do outperform regular hdd's , the SSD catch was probably made for the system that would have the OS loaded on a regular hdd and the small SSD to be used as the cache. If you use a small SSD to cache a larger SSD you might not see a performance increase like you would with a regular hdd. So if you got a 120gb or 240gb SSD then you could load your OS on it and be good to go. If you wanted you could still get a 60gb or less SSD to use as a cache. If you did do that I would only get a 20-30gb SSD for the cache.