During the last month, due to some testing we had to carry out with a software project, I needed to work with 64-bit virtual machines. Virtual Server does not support 64-bit virtual machines, so I downloaded a copy of VMWare's free server solution and decided to give it a try. After playing around with VMWare Server, I've had my ups and downs which I will try to contrast with my previous experiences with Virtual Server. Price
Both are free, no contest there. VMWare requires a registration process to obtain the product key for the server, which can be a bit of a hassle. Virtual Server requires a registration process as well but no product key is needed.64-bit Support
VMWare's server runs as a 32-bit process on 64-bit hosts and offers support for 64-bit VMs (read again, slowly and it will make sense). Virtual Server runs as a 64-bit process on 64-bit hosts and does not offer support for 32-bit VMs. Types of Virtual Hard Drives
VMWare offers virtual drives that expand as they become bigger or ones that are of fixed size. It does not offer what is known as Difference Disks in Virtual Server. These disks are amazing when working with lab environments or for multiple restore points, and is one feature I cannot believe is in some way or another on VMWare.Undo Disks
VMware and Virtual Server both have this option. The restore process under VMWare is easier to carry out than on Virtual Server.
VMWare Virtual Server imports Virtual Servers vhds seamlessly. It does, however, convert them to a big mess of chunks that is hard to maintain. Although Virtual Server does not import any other type of virtual hard drive from another reseller, there are tools out there that will do the job for you.GUI
Even though there are some clear advantages of having a web interface for Virtual Server, there should have been a binary to administer it. There are some new alternatives
out there that might work for Virtual Server, but the bottom line is that the 32-bit client for controlling VMWare's server blows any web application out of the water.
Overall, both are excellent products and the fact that they are free is amazing. I have grown so used to Virtual Server that I will continue to use it unless I have the specific need for a 64-bit VM, and when that time comes, I will hopefully be able to use Longhorn Virtualization.