I highly recommend using a SSD from OWC:
http://eshop.macsales.com/shop/SSD/OWC/
I recommend using an SSD for your OS Drive and install a Second drive in the optical bay.
If you can add another SSD even better. If not I recommend a Seagate Momentus XT 2.5″ SATA 7200RPM/SSD Hybrid Drive
Installing MacBook Pro 15″ Unibody Early 2011 Optical Drive Replacement
For a video tutorial I recommend clicking on the link:
http://eshop.macsales.com/installvideos/macbookpro_15_unibody_mid10_dd_h/
