I still remember that i'm have been using Virtual PC and Virtual Server back in year 2003. Back then , it is free compare to Vmware. Virtual PC and Virtual Server is just another software which ran on top of your existing operating system.
Here is some limitation of Virtual Server & Virtual PC which i know of:-
a) Limited to 32x guest operating system
b) Using only 25% of 1 processor.
c) Limited to 3.6GB of RAM per guest.
As time past by, Microsoft has finally come out with built in virtualization solution on Windows Server 2008 64 platform. Hyper V is a new a hypervisor based virtualization which do not run on top of the operating system. The child partition is directly access to the resources. The advantages of Hyper V is
a) Support SMP and 64 bit VM for guest.
b) Support more than 3.6GB of RAM per guest.
c) Support for mapping a LUN directly to VM
d) Hyper V snap in is a MMC based management compare to web based. You can install RSAT in Vista and Windows 7 in order to manage Hyper V.
However in order to install Hyper V, you need to fulfill this requirement:-
a) Hardware assisted virtualization. (Intel VT or AMD VT)
b) Enabled hardware data execution protection (DEP) to protect from malware read/write. (Intel-Execute disable (XD)/AMD-No execute (ND) )
c) 64 bit capable processor
d) Install with Windows Server 2008 -64x platform.
To make your life easy, here is some link to help you to build your 1st Hyper V server
DELL server which support Hyper V- http://www1.ap.dell.com/my/en/business/servers/hypervisor_servers/cp.aspx?refid=hypervisor_servers&s=bsd&cs=mybsd1
HP server which support Hyper V-
Intel Processor which support Hyper V-
AMD processor which support Hyper V-
For those folk who are using Virtual Server, start to migrate to Hyper V. Give Hyper V a try and you will be surprise how Microsoft improved on virtualization technology. Plus Microsoft going to lauch Hyper V R2 on 22 Oct 2009. If you need any assistance, kindly email to firstname.lastname@example.org.