SATA I vs. SATA II

I just bought a new Seagate SATA-II hard drive to add to my storage space.  Right now it's recognized as a SATA-I HDD in BIOS, which leads to two questions.  1)Is it worth the effort to change it/is SATA-II that much faster, and 2)How would I fix it so it's recognized as SATA-II? 

I have a suspicion it's the jumpers in back, but the way my drives are mounted in my case it would be a bitch to take it out just to change the jumper and find out that's not it.  So what do I do, /comp/?

>>13
I believe a lot\all of new SATA equipment has a newer snap-lock plug. Might be wrong though.

They're certainly not tough motherfuckers like IDE ribbons. Those require the combined strength of a thousand men to remove sometimes.