There's a big difference in the actual numbers. The old SSD's get about half the performance (because they're on Sata 3gb/s instead of 6). But, compared to a standard hdd, it's going to feel like a big boost no matter what.
My Cosair Force GT SSD failed after 6 months, Unfortuantly I had all my game saves on it... All gone sob! Skyrim, ME3, Simcity, etc. My fault, since I usually changed my documents folder to my data drive. (SSD was the OS drive)