In an obvious reaction to the release of VMware Server as free download, Microsoft has announced that it will make all of its Virtual PC products free as well, including the upcoming Virtual PC 2007 for Windows Vista when it finally arrives.
So what's the difference between VMware Server and Virtual PC 2004? The answer is quite simple really. VMware Server is much better, which it is why it is the market leader.
VMware, owned by EMC, runs on both Windows and Linux as the host operating system and supports virtual machines running a range of guest operating systems, including Solaris, Netware, Windows and Linux.