adding to ap's recommendations
you might want to try your hand at vmware workstation first if you are hesitent to upgrade This is because it will have a much smaller learning curve for you to work with as you are already familiar with a hypervisor on top of an os. if you ahve a small team and no time its the best solution.
For long term goals, esxi is the way to go. But that also means getting your hands dirty with some new concepts.