I am no expert, but I have just transferred Parallels 9 with win 7 pro onto my new MBP retina 13 inch OSX 10.9.3. from my old MBP also on OSX 10.9.3. Initially Parallels and win 7 would not display correctly at all. Some text was huge and some microscopically small. Eventually i went into Parallels win 7 pro configure and set the video at 'scaled'. It had been on 'best for retina'. Everything works great now and displays properly. I am just trying to help anyone else out there who may try and do the same. If I have flouted any rules on this forum; i.e. this is already written down somewhere then apologies, I did search but I couldn't come up with anything. Hope this helps someone.