Parallels, a division of Citrix, on Mac OSX is my preferred choice for Windows emulation. I’ve tried VMware Fusion but found it slower, less reliable and kind of flaky. HOWEVER, Parallels shoves ads which is REALLY annoying in a paid for product that costs USD$80. I’ve seriously considered ditching the product for this alone - truly offensive.
defaults write com.parallels.Parallels\ Desktop ProductPromo.ForcePromoOff -bool YES
Paste this in the terminal and it will disable the ads.
Michael Tsai - Blog - Turning Off Ads in Parallels.
Reddit - http://www.reddit.com/r/mac/comments/x0qgs/using_parallels_hate_the_popup_advertising_heres/