I did remove tack strips from a terazzo/concrete floor before refinishing the floor with an acid wash. You must not pull out the nails! You can take the woode out from around the nails and then use a dremmel tool to "shave off" the tops of the tacks. This worked beautifully. It left very smallbrown/rust dots where the nails used to be but who cares you are covering with tile. If you pull up the tacks there is the possibility that you will take huge chunks of the cement with the tack and you do not need that extra work. Good luck It is an easy fix and the Dremmel tool costs undre $100. Maybe a friend of yours might have one with a flat disc like head for grinding off the tack heads.