SSD on Macbook mid2010
As johnfinn68 answered in this Apple Discussions post:


  To determine [the bus speed of HDD and SuperDrive slots], go to the apple icon, about this mac, more info,select Serial ATA, then look at the (on mine) Nvidia AHCI and see the Link Speed and Negotiated Link speed.  The default one shown is the HDD, you need to click on the other AHCI channel to see the optical drive specs.  This will help you determine where to put the SSD.