About %90 the speed of the SSD but with the space of a large drive like your 1TB....
I use a 60GB Agility 3 as a boot drive and then have another one caching a 2TB games drive and it works remarkably well.
Its called Intel Smart Response Technology and here is a link that explains it from intel. A google search of Intel IRST should bring up some reviews.
Intel IRST
Intel aimed it to be used to cache a boot drive but it can be configured to cache a different drive as well. It can take some setting up but is well worth the effort as you will essentially end up with a 1TB drive running at about %90 the performance of a standalone SSD.