Windows 8 versions circulating to date are trial versions, so there is the option to return to Windows 7 unless you take out a full backup of the boot partition or perform a full reinstallation.
If you want to try Windows 8 it is best to use a virtual machine, you can use programs like VMware, VirtualBox or similar, check out the following posts for more information:
- Manual step Virtualbox.
- How to install Windows 8 in a virtual machine step by step.
- How to install the Guest Additions on Windows 8 virtual.
In addition to reasonably use Windows 8 in a virtual machine, you need a machine with at least 2 GB of RAM, the more the better, preferably a multi-core processor that supports virtualization.