It's a SATA II hard drive, not SATA III. SATA II's hard drives are backwards compatible with SATA I's so it should work for your Toshiba L455.
A good wiki search about SATA stuff can help understand the situation. Youtube videos can help with locating, identifying, and replacing the drive too.
Few, old computers (I'd say around 2000 or before) still use the IDE hard drive type but it's certainly rare these days.