I've been meaning to try VirtualBox, the free x86 virtualisation product from InnoTek, and a comment to my previous Vista/Ubuntu post has pushed me into it.
Of course, I can't just put a Windows OS on my Ubuntu machinery - don't have an unused Genuine Windows Advantage XP or Vista, and to reuse anything would be against the licence. And I couldn't run the more inexpensive versions of Vista in a virtual environment at all, even if I'd paid full retail, because that's against the licence too.
So I decided to put Ubuntu on the Vista dual-core Centrino laptop.
And in the word of Microsoft's marketing department: wow. Very impressive.
Not perfect: I did have a problem with screen resolution -- the install only worked initially in a 640x480 window -- but that was fixed by adding the helper apps from InnoTek and running them as root, which took about a minute once I'd twigged.
Also, the networking needed to be explicitly enabled: another click. And I found it frustrating that you can't apparently change virtual machine settings, such as unmounting an ISO image from the virtual CD drive, on the fly, but that could be unreasonable of me.
But I did, in the space of about an hour, install and correctly configure a world-class modern operating system on top of a apparently reliable, efficient and very professional virtualisation layer, using only open source software.
(Charles Mclellan has just done something very similar, only with Gutsy and VMWare on top of XP on his World's Biggest Desktop Machine. That worked without a spot of hassle)
Haven't had time to do any performance testing, but subjectively, Ubuntu running FireFox and OpenOffice.org in a VirtualBox machine under Vista appears more responsive than IE and Windows Office running natively under Vista. I'll try and think up some way of benchmarking that - would be very interesting, and I can't exclude the possibility that I'm expecting them to work better so that's what I see.
But If you've got a gig or more of memory, a chunk of spare disk space and a broadband connection, you really should check this out.
Might even put a Dialogue Box together around it. Charles?