I have one, just purchased it from TigerDirect.com
it was $123 with S&H no Tax best deal around and I looked hard.
It has made the boot up and shutdown much faster, also some apps run much quicker, although I have a large iTunes library it has made it run quicker but not all that much, but everything else is good and less vibrations and quite compared to my other 7200 RPM HDD.
I am very pleased as I have had Hitachi, WD, and Seagate drives even Toshiba, this performs best from what I can tell.
There is no way to access the 4GB SSD drive, the Seagate drive does it automatically so do not think you can load your OS just on that.