Supportability and licensing are key when it comes to virtualization a BizTalk Server 2010 production or any other environment. It also provides a much easier scalability when it comes to adding server or resources. virtualization of the BizTalk servers are getting more and more common for all the different viritualzation platforms as the support get better. More and more big companies moves BizTalk over to the virtual platform to keep costs and downtime down to a minimum.
to SQL Server Enterprise, BizTalk Server 2010 ENT can be licensed for
unlimited virtualized processors that are available on a single physical
server. As customer you will be required to license the number of physical
processors on a server.
In case you desire to build your own BizTalk Server 2010 virtual machine for learning purposes you can use Hyper-V in case you have Windows 2008 R2 with Hyper-V to your disposal, or an alternative like VMWare or VirtualBox. The latter are appropriate in case you want to build a virtual machine on a laptop or desktop with a client OS like Vista or Windows 7. You can download the ready made VHD, yet you have to convert them either to VMDK or VDI format.