4. Which server virtualization vendor currently offers the broadest x86 virtualization functions and mature virtualization management tools?
c) IBM Advanced POWER Virtualization
d) Microsoft Virtual Server
VMare has been in the game longer than anyone else in the recent x86 virtualization push. But that is not to say that everyone else is just playing catch-up. Other vendors' platforms are useful for different purposes and boast their own advantages, such as open source code, OS specific compatibility, and chip specific compatibility.
Then, of course, there are the free versions might be viable options if price is a concern or if a simple testing platform is all that's required. At any rate, the VM market is filling up with a number of vendors offering virtualization with their own stamps. It is up to consumers to decide what their data centers require.