You want to check out Windows 8 and don't have hardware to spare, can't run virtual or if just want to check if your computer can run Windows 8 ?
Then you might try Window 8 To Go. You need a USB drive with some space available, running it on USB 3 will of course give faster speed, but I have runned it on several USB 2 disk (memory stick and USB 2/3 often got to hot, so I use disks instead) without problem. I runned the developer preview on a Lacie Rugged Disk 500 GB (7200 rpm) and did several session on it at NIC 2012 and Utmessan on this solution without any hickups or problems
I created a guide that still works on the newer relases: http://olavtvedt.blogspot.de/2011/12/windows-8-to-go-or-how-to-test-windows.html but it doesn't have the disk policy, so you will have local disk access on the physical computer that you boots up on.
An offical way off doing it can be found here http://social.technet.microsoft.com/wiki/contents/articles/6991.windows-to-go-step-by-step.aspx
Another solution are using VHD boot, to see an excellent guide you can go here: http://www.zdnet.com/blog/bott/how-to-use-a-vhd-to-dual-boot-windows-8-on-a-windows-7-pc/4847?timestamp=1340785506