I bet it's not even close. If it's a 64GB drive I bet it formats out to about 60GB. Then throw on not just the OS but everything else that ships and it's probably closer to 53-56GB free. Of course I'm guestimating so hopefully someone who's actually used a 64GB drive around here can chime in.
The way some apps build a safety net around you (iPhoto making multiple copies of every picture in your collection, iMovie saving clips you delete, etc.) I just can't see a 64GB drive doing the job unless it's truly a browsing & office only type of use.