Virtualization on the Mac platform has a rather lengthy history, starting with the original Virtual PC from Connectix, which emulates an x86 PC on the Power PC platform used by Apple then. With Apple's switch to Intel-based Macs, it has only gotten easier for virtualization, since the new Intel processors have virtualization support in hardware that should improve the performance of the virtualized operating system. Meanwhile, Virtual PC has gone purely Windows only, with its present owner, Microsoft choosing not to have a port of the software for the Mac, citing as a reason that Mac users have no lack of options when it comes to running other operating systems.
This is actually quite a valid claim as not only does Apple provide a solution themselves with the currently downloadable beta version of Boot Camp (slated to be in the upcoming Mac OS X 10.5 aka Leopard), which requires a separate partition for Windows XP with Service Pack 2 or Windows Vista on an Intel Mac, there is also a company offering a virtualization solution for the Mac since 2005. That is none other than Parallels Desktop for Mac and its third revision was released in July 2007.
The difference between the two is that while Boot Camp is akin to having a dual boot of Mac OS X and the Windows operating system on different partitions, Parallels is a true virtualization tool using its own hypervisor technology to virtualize all the hardware devices and allows for the installation of multiple operating systems as a guest OS over the host OS (Mac OS X in this case). It is not limited only to Windows but also compatible with other OSes like various Linux distributions, Solaris, OS/2, etc.
VMware enters this mature market with all the pedigree and experience of being a market leader in virtualization technology. For once, it is in the role of the challenger against the incumbent and more established Parallels Desktop and hence, the onus is on the company to prove that its solid track record in virtualization can prosper in a more consumer centric segment, particularly since VMware's products have been focused mainly on the enterprise and power users.
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