Once you've downloaded the ISO image of the operating system, you can either install it to a PC, dual-install it with Windows or what have you, or just give it a try from a USB stick or CD. On a Windows system, you can also try Ubuntu 11.04 within Windows using Wubi. With this approach, you treat Ubuntu just as if it were a Windows application and run it within Windows. There is no such "run with the operating system" option for Macs. You can, however, run it on a Mac or a Windows PC with a virtualization program such as such as VirtualBox or VMware Player.
Of course, if you're already running Ubuntu, you can simply update your older version. I was able to upgrade my Ubuntu 10.10 without any trouble.
The new Ubuntu will run on any PC from the last ten years. I've got it running on several PCs and laptops here at my office and it does great on even my no-name 2006 PC with a 2.8 GHz Pentium IV, 1 GB of RAM, and a 60 GB hard drive.
Putting Ubuntu 11.04 through its paces
To kick the tires on Ubuntu 11.04, I installed it on several different systems, including the aforementioned generic PC, as well as a Dell Mini 9 netbook, and my Gateway DX4710. This PC, my main test box, is powered by a 2.5-GHz Intel Core 2 Quad processor and has 6GBs of RAM and an Intel GMA (Graphics Media Accelerator) 3100 for graphics.
The first thing I noticed was that Unity is designed for 16:9-sized interfaces. You can still use it on an older 4:3 display, but it looks and works best on a 16:9 display.
If, by the by, you decide you can't stand the Unity interface, you can switch back to the old Ubuntu GNOME 2.x style interface by just rebooting and choosing Ubuntu Classic from the bottom of the logon screen.
Although I wasn't able to test it, Unity also supports multi-touch via Utouch. A few months back, Shuttleworth told me that multi-touch would be be integrated into Unity and applications. "I think in the near future all laptops will have sophisticated multi-touch hardware. All the hardware vendors that are working on touch are talking to Ubuntu." After one look with the interface, I believe it. On the netbook in particular I kept wanting to touch the display as I would my iPad or Nook instead of using a mouse.
After playing with it, I found that the Unity interface is simple. Indeed, many Linux users will find it far too simple. That's because you can't really get your hands dirty with this operating system. Or, rather, you can, but like with a Mac, to get to the technical nitty-gritty, you need to dig past the interface. This makes Ubuntu 11.04 great for new users, but savvy old Linux fans might find it too pretty for their tastes.