Parallels and VMWare Fusion have been two main applications for virtualizing Windows (and other OSes) on Mac OS X. Parallels was the pioneering product here. I was a loyal user since 3.0, which was 4 upgrade cycles ago. Parallels has always been great software that just worked. Starting from version 5 or 6, the software shows you ads as you start it up. Yes, you heard me right. A full, paid version displays a glaring, nasty "buy-me-now" ad on startup, complete with Facebook links to "share" it. Yeah, right. The ad windows have a "Disable" checkbox, which does nothing. It prevents that specific ad from appearing, but the next ad campaign is going to spam you in the face. Issuing a defaults write com.parallels.Parallels\ Desktop ProductPromo.ForcePromoOff -bool YES command in the terminal will get rid of the ads until the next application patch. Then you will have to go to the terminal again. The developers do not publicly supply the defaults key information. The anti-ad threads on their forum are some of the most active ones, and they get strategically deleted and pruned by the moderators. Showing these ads in a hamfisted manner is definitely a business decision that someone made. See this, for example http://forum.parallels.com/showthread.php?t=258991 (if the link gets killed - it means the thread got silently deleted). I submitted a bug report regarding this, because this is a bug, and got no response. My own business decision is that Parallels 7 is the last update I purchased from that company. I am switching to VMWare Fusion, even if that means I have to readjust my workflow.