I recommend VMware 10 because it has full support for Windows 8.1, used it without any problems. so try it since VMware 9 didn't cause problems on your hardware.
Don't think so. These three you mentioned are most known tools for virtualization. I personally use VirtualBox for testing all Windows leaks and use VMWare for testing OSX as it easier to set it up for OSX. As for the Mouse issues on VirtualBox, you just probably need to install newest guest OS Tools
Just buy a set of backgammon and play with him, maybe if you loss enough games, he will be happy and give you a good raise.
Thanks a lot for the tip's ! @PaulDesmond: Possible the best solution for compatibility, but just to much work. @Super User: The right-ctrl - key didn't work proper to catch / release the Mouse-Pointer. @napalmguy Yeah, seems to be the best solution. @FaiKee: Pay Rise from my Boss ? Unfortunately not.
My only "slight" issue with VMware Player is that it doesn't seem to be easy to start up multiple virtual machines. I can start one VM up without problem, but the library window goes away upon starting that VM, and I can't select another. Calling some vmware exe from Run did re-open the library, but it kept complaining about how the existing VM was open. I could just be missing something though...