Virtual Machine

If you want to run many operating systems on a single operating system than this is possible by creating virtual machine for every operating system that can provide resources virtually. However there are software present that can do this for you easily. Software for creating virtual machines are VMware and VirtualBox (Oracle).

VirtualBox(Oracle) is free of cost and in VMware there are two softwares VMplayer and VMware workstation, VMplayer is also freeware but workstation is paid.

However comparing these two will conclude that Virtualbox is more faster and will provide you more professional facilities such as remote desktop service, 8 network adapter etc but VMplayer is more easier to use and is user friendly.

Startup and shutdown time is lower in case of virtualbox, vmplayer taker more time to open and shutdown because virtual box as faster disk access time.File transfer is almost same in both case and also resouce usage is almost same according to the configuration of guest OS. But vmplayer uses less ram. 

VMplayer is bigger in size and oracle virtual box is much smaller.
VMplayer has big advantage of Win 7 aero support.

VMplayer installation tutorial