Server Virtualization

virtualbox or xen Not sure what you mean by a light server virtualization software? Neither of these use a whole lot of resources, but the virtual instance by its very nature will.

Virtual box will let you keep your current Operating system (ubuntu, windows). You can create and run VM's from these Operating systems.

Xen is a full OS replacement. You will have to install it as a new OS to a system.

I've used Xen, VMware, and VirtualBox. I have had the best results with VirtualBox. It may have changed, but it used to be that you could not install a native nVidia video driver on a system running Xen, so you could not get full use out of modern displays. That may have been fixed (it was 5 years ago when I last used it). That's why I changed to VirtualBox. I've been using it ever since on both Linux and Windows hosts, running a variety of operating systems including Linux, QNX, DOS, Windows, Solaris, and BSD Unix. Works great, and it is FOSS (Free and Open Source Software), so you can even get the source code for it.

Agreed. I only suggested Xen because it is easy to install in openSuSE. I prefer VirtualBox.

Try openvz, vmware or xen. All are best. But if you want for study purpose then I will suggest vmware and xen hypervirtulization. Both allows different guest OS.

for study use virtualbox its os level virtualization and has a good UI , dont need to learn anything beyond the virtualization ,

i use VMware and Virtual Box, but it is a little bit heavey than virtual box, so i also prefer virtual box for vistualization

i would suggest virtualbox as well. for study purposes it should be sufficient.