VirtualBox 3.x is the best version of Sun’s virtualization software yet. I say that for a variety of reasons, including the limited, but much better, direct3d support which allows for certain graphically intense applications and games to be run in the virtual environment. But, there is one more killer feature that I have discovered: seamless mode.
Seamless mode integrates nicely with the host operating system. In my case, I am running Windows 7, RC1 as the host and Windows XP Professional, SP3, as the guest. In seamless mode, I can see the XP task bar sitting on top of the Windows 7 task bar, so it looks like I have two task bars. I can run Windows XP apps right alongside Vista/Windows 7 apps. This gives the APPEARANCE of a seamless integration, however, there are limitations to that ‘seamless’ integration. You cannot, for example, drag and drop files from a Windows 7 explorer window to an XP explorer window. You can, however, specify shared directories in the settings dialog for the virtual environment. While it is not completely seamless, it is pretty darn close. It is also a viable alternative to the ‘XP Mode’ that Microsoft is offering for Windows 7 Professional and Ultimate editions. The caveat here is that you must supply your own, valid copy of XP whereas the Microsoft version supplies a fully licensed and activated XP.
The more I use VirtualBox the more I like it. It not only solve a few compatibility issues, it also provides a sand box for me to play around with other operating systems without ‘committing’ a real machine to the new OS. It will allow me to play around with Google’s Chrome OS if and when that comes out.