I recently installed VMware ESXi on my abandoned server, as it would not start any GNU/Linux distribution for some strange reason (during udev startup.)
ESXi installed quick and set up easily. Set the password and configure the IP and I could let it be, physical access wise.
From there, I simply installed the management software, VMware vSphere Client. Then, I deployed a Virtual Appliance for fun. After downloading, right from the management software, the appliance was ready for me to play with within minutes.
From there, I sent an ISO to the server and installed a Debian 5 virtual machine. I also used the physical server’s DVD drive to install OpenSUSE 11.
You can also take VMware Workstation virtual machines to your server effortlessly.
Right now, I’m setting up the Mobile Access appliance, but the server is on a 10mbit switch and a weak wireless connection, so it takes time to send the disk.
Overall, I give a recommendation for ESXi if you have a brand new server and want to virtualize. It’s free from VMware’s website: vmware.com