I would like to add an Optibay type thingy to my superdrive slot, and add an OWC SSD 3G drive as my boot drive. Is 40 GB enough? Or will 60 GB be the better choice? (Or perhaps the 115GB version)? Price-wise the 40 GB is around $100, the 60 GB is about $120, and the 115 GB is around $190. I plan on having the OS, all apps, and the home folder on the SSD, with the iTunes, iPhoto library and all other data on the HDD. I've heard different things about how SSDs need 'more' free space than the average HDD, but I don't know if that's true. How much space does OS X take up in general?