I've been excited by the idea of a truly portable operating environment for a while. I'd love to be able to sit down at any workstation and fire up my world -- my documents, my web browser bookmarks, everything. We're a long way away from that still (I'd love for everything to be in some sort of reliable, secure, always-on inexpensive cloud, with native-desktop-speed access to that...), but getting closer.
I'm theoretically entering a situation where I won't have access to my personal computers, but will have access to workstations in an unknown but presumed locked down configuration -- pretty typical for many who access the world through libraries, university (or high school) computer labs, want a way to catch up on personal email during lunch breaks at the office, at a business center at a hotel, whatever. (Always adhering to the local usage and access policies, of course!) Being able to fire up my VPN and encrypted volumes to have secure access to my work is a Good Thing.
As such, I want to have an environment (Windows with Cygwin, I guess, to straddle both worlds but still have native access to, e.g., Acrobat Pro and Microsoft Office, two essential tools for a lawyer, though I've used scan2pdf and OpenOffice.org with some success) I can carry with me and run as an unprivileged (non-administrator) user.
I had high hopes for VMware ACE, but alas it requires the installation of VMware Player, which requires administrator access. MokaFive and its ilk all seem to likewise require admin rights. So far, the only real option seems to be QEMU, through Qemu Manager. So far so good, except I think I found an issue with the "File Transfer" functionality -- when using PASV mode it reports an IP address of 127.0.0.1, rather than the 10.0.2.2 the client will need to connect to. It's also not quite as fast as VMware, but otherwise appears to be as capable as I need it to be, especially once I transferred it from my fast, but nowhere near native hard drive speed, USB drive onto my laptop's internal drive for the purpose of setting up software. (I'll move it back to the USB drive for its intended use, obviously.)