Christian Saborío has posted his experiences of comparing Virtual Server and VMWare Server.  You can read more in his post “Virtual Server and VMWare Server“, and a snippet is below:

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…

…The bottom line is that 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

PS:  Fanboy’s and Propellorheads behave!  I don’t want to start yet another unholy war of Red vs Blue — I’m still recovering from last time  :)