VMware Workstation

Yes, free is always good but not necessarily better. It all depends on what you want to do with virtual machines and whether the product provides you with the mandatory features that you seek. VMware Workstation is geared towards developers, testers, trainers and people who just want to tinker with operating systems and environments.

Considering all the additional features you get over other alternatives, $189 (heaps cheaper for students, educational institutions etc) may not be a lot of outlay if it saves you time and effort.

The information of zzzcrash "VB guest OSs can only use one processor" is wrong:
If you configure a Virtual Box VM you can choose much more than one processor, see the screenshot in http://alternativeto.net/desktop/virtualbox and the help information of the VirtualBox:
"Starting with version 3.0, VirtualBox supports symmetrical multiprocessing (SMP) and can present up to 32 virtual CPU cores to each virtual machine. You should not, however, configure virtual machines to use more CPU cores than you have available physically."
I know both VMware Player and Sun VirtualBox, but Virtual Box is in my opinion more user-friendly than VMware Player.
In comparison Virtualbox has the advantage of its many languages, better commented configuration, quicker installation and quicker running of guest OS's and its applications, see http://ww1.4hf.de/2008/08/virtualisierung-desktop-virtualisierung-im-vergleich.html .
Additional VMware Player requires 3.5 times as much space on the hard disk as Sun VirtualBox:
VMware Player 361 MB, Sun VirtualBox only 102 MB, see http://screencast.com/t/YjY0ODdkNW

Tough to give VMWare the edge over Virtualbox, considering that VMWare costs money, but there's no doubt that VMWare is better. Guest OSs can utilize my dual-processor (VB guest OSs can only use one), and I think it's a little more user-friendly. Virtualbox is a great free alternative, though: wouldn't shell out the money for VMWare unless the difference between the two is that important to you.

No doubts Virtual box (SunMicrosystem develeloped) is the best alternative to VMware here you can try the latest version

tips-linux.net/en/content/virtual-box

No comments. VMware is just the #1 virtualization platform both in the Linux & Windows worlds.