Well 64 GB would cover a bit more than the bare essentials of the OS: it could hold some commonly used programs and games also. If you store date of any kind (pics, music, etc) you'll certainly need to retain that second HDD for that. The 64 GB crowd is more or less those looking for the "entry level" SSD experience with just enough for the essentials without spending a ton on a larger SSD. If you can afford a larger SSD, that would give you more headroom. Keep in mind it's best to leave a bit of free space on the drive.