Note that when you’re using two identical (size) drives then you could consider a RAID-0 setup which will be wicked fast, specially when using SSD drives. I really like speed, so I went with another 160Gb Intel SSD (probably not for everybody’s budget), but if you’re planning to just use it for massive storage then a regular 2.5″ harddrive as well offering more storage capacity at a much lower price. The choice of drive is completely up to you.
This link will help you identify the MacBook Pro model you have … For older models you’ll have to do some homework to figure out if the optical drive is actually using SATA. Newer models, and I believe any of the unibody models, will be equally easy to convert. If you have a MacBook pro like I do (15″ mid 2010 MacBook Pro a.k.a. MacBookPro6,2) then this guide will work without even having to think. You will have to pay attention here – some of the older MacBook Pro’s appear to have a PATA (classic IDE/ATA) connector and those will not work with a SATA disk.
