So, why is this beneficial? How many times has a system that you owned or used crossed that magic threshold where suddenly, after adding or updating some software component (or getting nailed with some malware), the system becomes unstable. You start getting error messages and things start routinely crashing and you have no idea what the source of the problem is. The only thing you know is that the only way out is to start from scratch again; wipe your system's hard drive out, reinstall all the software (if you can find it); and hope that there's a way to preserve all of your customizations in all of your software (everything from bookmarks to specialized preferences, etc.). I can pretty much guarantee you that the cost of this process in terms of your time and even worse, what gets lost along the way, will exceed the cost of the $180 it costs to buy VMware Workstation. In other words, it's what they call short money. Here's why.
If you do what I do, which is to set up virtual machines by software groupings, the chances that some new component or malware will wriggle its way into your box and destabilize the rest of your system or other software is greatly reduced. In fact, it's practically eliminated. For example, after installing Windows into my first virtual machine and making sure that "base version" is up-to-date with all the necessary updates (security and otherwise), the first thing I do is create a clone of it. Then, I go into that clone, open up Internet Explorer, and customize it (bookmarks, IE-specific plug-ins, etc.) for usage with all the Web sites that work better (or only) with IE. Then, using VMware's cloning feature, I clone that virtual machine (now I have three VMs in total) and put that "backup" away for safekeeping.
From that point forward, I use the second virtual machine (the one with all my IE customizations) as my production virtual machine for all of my IE-based browsing. If, for example, the IE plug in for Real gets corrupted (this has happened to me already) or something goes terribly wrong with the IE setup, I simply delete the entire virtual machine, go back to my backup (the third VM), clone it (essentially recreating the second one), and I'm right back to where I started with a nice clean, uncorrupted VM. My "IE-only VM" is just one of my software groups.
Another one of my software groups is just for doing Web-based e-commerce. Using that VM, I never ever install any downloads or other software that might somehow come with spyware. I use my "E-commerce only VM" just to visit specific sites that I often do business with. I never have to worry about any other software looking at my cookies, my cache, my autocomplete info, or anything. I have another VM/software-group for all my Web-based e-mail. What if you have three different Gmail accounts and you want to keep all three open simultaneously? No problem. And so on and so on. You get the picture. Each virtual machine is like a completely separate computer and should be thought of and treated as such.
Once your software groups are virtualized, there's another unbelievably significant benefit. I don't think I know any computer users who haven't at one point or another had to switch machines. If, for example, the one they have breaks and they get a system to take its place (either a new one or a loaner), bringing that system up-to-speed in terms of personalizations can take forever and even then, it may never be just the way that other system fit like a glove. But, if that new system has a copy of VMware Workstation on it or it's running VMware's free runtime, then all the user needs is a copy of of his or her various virtual machines and being back up to speed takes, oh, about 10 or 15 minutes at most (as long as it takes to copy the virtual machines to the hard drive). Personalizations and all. Just imagine if your the IT person who had the prescience to put VMware on everybody's system's and show them how to use it. You'd be the company hero on pretty short order. Yeah, VMware is just that good.
Is it perfect? No. For example, buying a copy may only cost $180. But each virtual machine takes up additional hard drive space and the more of them you run simultaneously (side-by-side at the same time), the more memory that's required. But chances are you won't have to run all your virtual machines at the same time. I don't. For example, I don't have that many sites that I go to that require IE. So, I only run my my IE-only VM when I really need it. Another problem, depending on how many VMs you have is keeping them all up to date with Microsoft's software updates. Eventually, I'm hoping VMware will come with a special management feature that handles retrieval of those updates and then distribution to each of the VMs a single-click process.
Finally, in the wrong hands, VMware can be workaround to anti-piracy technologies such as Microsoft Windows Product Activation (WPA). A single clone along with all the applications that have been installed in it can be copied to any machine (especially since the VMware runtime that's needed on those machines is free).
Also, there's the dicey question of Windows license misuse. Technically speaking, you're not allowed to clone your copy of Windows and run those separate instances simultaneously. Even if it is on the same machine. One reason is that your system could be used (if you wanted to) as the equivalent of a multi-user Citrix box where different people can come in remotely and remotely use one of the virtual machines. This is not what Microsoft had in mind. So, while it's technically feasible to set up all these clones, the question of whether it's legally feasible and what Microsoft may end up doing about it down the road (either technically or legally) could throw a wrench into things. It's something to stay on top of. Even so, my number one recommendation now when people are getting a new system is to get the biggest hard drive possible, get as much memory as you can afford, and to install VMWare Workstation before they do anything else.