How can I read/write to several hard drives created on windows 7,8 from OS X My PC's hard drive - running w8.1- crashed. Bought a mac mini and now trying to retrieve files from crashed disk (and others). All drives have read only permissions, with no locks showing in the get info windows. Is there a way to change permission w/o losing files?
The "read only" status has to do with the UUID of the files on the drive no longer matching what is coming from your Mac.  So, basically, you have to "orphan" those files.

Here is a good writeup on how to do it, but note that this is an UNOFFICIAL method and not sanctioned by Apple.

How to Enable NTFS Write Support in Mac OS X