I encountered none of the installation or conversion problems some posters here experienced, but there were some bugs in the previous 4.0 build that were relatively minor (if annoying) that this release seems to have fixed. Even with those bugs (some freezes, delayed quitting) 4.0 is a big improvement over previous releases. As for the VM Fusion vs Parallels issue, Fusion has been problematic in the past recognizing some USB devices and network printers for me. There were manual settings I had to apply that didn't work consistently. Parallels did the job more deftly and version 4, is vastly improved. I continue to run comparison tests between the two, and for my money Parallels still has the edge for immediate recognition of devices and settings for mouse, keyboard, printer, camera. I have no stake in either company, I only want to use what's fastest and most efficient, and Parallels' more intuitively elegant design doesn't hurt any. It's good to see that this 3540 release makes Parallels even more solid.