Make sure you have Hyper-V installed to run this virtual machine. You will also need a 64-bit system with hardware-assisted virtualization enabled, as well as data execution prevention (DEP).
Download SQL Server 2008 R2 VHD
There are 5 parts to be downloaded in the link given above. Once downloaded, self-extract the RAR file, accept the EULA and import the VM into your Hyper-V.
Note: To connect to the internet using this VHD, you will manually need to configure a virtual NIC.