VirtualBox on Core Duo 2 Vista 64 Host, Ubuntu Guest: Very good performance.
This surprised me: My laptop is an HP DV4, with 4 GB of RAM. I am watching a DVD (Foyle’s War: The German Woman”) playing on Windows Media Player, running on Vista 64. At the same time VirtualBox 3 is running, and on VBox Ubunto 9.04 is running.
What got my attention is that I upgraded Ubuntu (56 sundry updates) on VBox while also viewing the movie (on Vista) and using Firefox 3.5 to read identi.ca. It all ran smothly. Very smoothly.
Virtualization, when you have a decent CPU and lots of RAM, has performance so good that you don’t care. I like that a LOT.