You don't have an extra PC/notebook/what-ever laying around and don't have access to one with Hyper-V (or other hypervisor) but you have access to Azure via MSDN (or other route)? Then you can start playing with Windows 10 in about 5 minutes...
Microsoft Developer Switzerland News - Try the Windows 10 Technical Preview now without having to install it first!
If you are willing to try it out without having the hassle of upgrading one of your PCs, you may want to consider the possibility of having it running “in the cloud” and accessing it through a remote connection on your PC. This very little invasive approach requires only the Remote Desktop client and minimizes the requirements on your hardware.
All you need is a valid MSDN subscription and access to Microsoft Azure.
On Microsoft Azure you can find a fully preconfigured virtual machine, to which you can connect in just a few clicks. Below, you can find the required steps.
First, you need access to Microsoft Azure. If you don’t have a subscription yet, fortunately there are a few ways to do so for free.
How to gain access to Microsoft Azure for free:
... and this post walks you through all the steps (and it's not hard at all). I did it while on the train home today, how cool is that? :)