I've come across an interesting alternative to parallels/vmware that uses very little CPU/memory. If you are like me and was contemplating parallels simply to use MS office, there is an alternative. I'm posting it here because it might help someone else too. This all works using my 15" rmbp late 2013. If you have an old PC running windows 7 ultimate/business or windows 8 pro, you can use microsoft remote desktop to control that computer from your mac. You can use it in fullscreen or set a scaled custom resolution of half the screen and use it in a window. You can then run ms office on the remote machine and you have a full copy of ms office on your mac. If your old PC is not running one of the pricer versions of windows, you can use VNC. I tried tightvnc on the PC as a server and realvnc viewer on the mac. It works just as well as the above method. I'm running this on a dell venue 8 pro, which is a couple hundred dollar windows 8.1 tablet that comes free with the full 2013 office home and student. The downside is that this method will only work well on a local network. However, that is fine for my purposes. To open local files on the mac, you can share your drive to the PC and allow the PC to open files on your mac. The upside is that this method uses very low resources on your mac, so you will get good battery life and the fans won't run very hard. It also uses almost no HD space. This method is free, so no yearly fees to parallels/vmware.