Windows Server 2008 (download) is the best OS to be released till date from Microsoft's stable. So here’s the steps of how to set up Windows Server 2008 to look and fell like its desktop counterpart Windows Vista.
1. Enable Hardware Virtualization — if your system is a x64 machine with hardware virtualization capabilities and you want to run Hyper-V. Just enable it via your BIOS setup.
2. Being a server OS Windows 2008 carries with it basic graphics and audio drivers, to enable the "Aero" experience on Windows 2008, install the latest Graphics and Audio drivers.
3. The Desktop Experience Feature enables a bunch of stuff that is by default present on a desktop OS. Most importantly it includes Themes, Windows Media player and the Aero related features. You will have to enable it form the Server Manager. The "Turn Windows features on or off" / "Add remove windows components" has all been rolled into the Server Manager now: Server Manager > Features > Desktop Experience
Installing the Desktop Experience feature does not enable them. You have to manually set them up.
4. To enable Themes you will basically have to enable the Themes Service. Again being a server OS it is not enabled by default: Services.MSC > Themes
Set the start up type to Automatic – Enabling the Aero Theme. For this go to Control Panel > Personalization >Theme and select Windows Aero
More info: MSDN Blog