oreilly.comSafari Books Online.Conferences.


AddThis Social Bookmark Button

Run Multiple OSes with Virtual PC and VMware Workstation

by J.W. Olsen

If you occasionally need to run multiple operating systems, Microsoft and third-party dual-boot products beat buying multiple hardware systems. But if you must frequently jump between operating environments, the trump cards are virtual-OS products, which run multiple guest environments on one host system. As a bonus, you can run alternate configurations of the same OS simultaneously, and, if a guest OS becomes corrupted, you can discard it without harming the host system. Visiting malicious web sites or installing and testing unfriendly apps and cleaning up the mess on your system can quickly pay for either product.

For years, the acknowledged leader in this product category has been VMware. But after the acquisition of Virtual PC by Microsoft, it's now a neck-and-neck race. This article compares the benefits of the two products.

The price of admission for these products isn't cheap. Although the direct cost is eminently reasonable, your computer must have generous system resources. Also, you generally must license each iteration of an operating system and the software that you install on it.

Your first decision in evaluating VMware and Virtual PC involves the host and guest operating systems you plan to run. Not surprisingly, Virtual PC emphasizes support for Microsoft OSes. Your host system must run Windows XP Professional, Windows 2000 Professional, or Windows XP Tablet PC Edition. Guest environments include essentially all Windows systems back to Windows 95, MS-DOS 6.22, and recent implementations of OS/2 Warp.

Meanwhile, VMware requires a host running a recent version of Windows or one of many Linux flavors. Guests may be most Windows OSes back to version 3.1, MS-DOS, and many Novell, Sun, FreeBSD, and Linux OSes. (See the vendor's web site for the extensive list of alternatives.) For this story, we tested both products on a Windows XP Professional SP2 host with many personal configuration changes and installed a second, out-of-the-box instance of the same OS as a guest. Thereafter, we changed each instance without affecting the other.

Related Reading

Test Driving Linux
From Windows to Linux in 60 Seconds
By David Brickner

We were delighted with how both products detected and supported hardware and other resources of our homebuilt test bed system. However, each product has related caveats. For example, neither permitted access to a legacy floppy disk drive through the guest. So we had to copy data from the guest to the host (a quick process if needed only occasionally), and then copy the results to the floppy disk. Be sure to check documentation for both products to ensure that your requirements are met.

Nowadays, disk space is mostly a nonissue. Just add the amount of space you want for your host system and all guest systems you plan to install, and then add a fudge factor to allow for Virtual PC or VMware itself and for unanticipated future needs. But remember that you can discard a guest OS and repurpose its space at any time.

RAM is the primary concern. Note that, unlike with hard disk space, for RAM you only need to factor the requirements of your host and the guests you want to accommodate concurrently. So if you install two guests but run only one at a time, consider the requirements for your host and your more demanding guests. Of course, your needs will vary dramatically depending on the apps you want to run on both your host and guest environments. For example, our tests involved word processing, modest spreadsheets, and other relatively undemanding tasks, so 1GB was adequate as a reference point.

However, add a fudge factor for RAM, too. After accepting the installer's default recommendations of each product, based on the Windows System Information applet on the guest, each program gobbled up more than 100MB of RAM for its own purposes. So in our test case, 1.5GB would be appropriate.

Both products recommend a minimum processor speed of 400MHz, which we found adequate for our purposes. But again, you must evaluate the apps you'll run. One difference is that Virtual PC requires a level 2 cache. Meanwhile, VMware claims support for multiple processors, though only for Windows NT 4.0 and certain Red Hat Linux guests. We tested on a dual-processor system but did not install and evaluate those guests. So the dual processors offered no advantage.

Both products installed painlessly and fast, but installing guests was a different matter. The speed of installing guests depends on your RAM and CPU, of course, but installing a guest on our test bed took nearly three times longer for Virtual PC than for VMware--a key factor if you anticipate installing many guests, or removing and adding guests frequently.

Tip: VMware's installer warned that Windows' autorun CD feature may be a problem and offered to turn it off. We learned the hard way by ignoring the offer. However, with a little tinkering we successfully installed a guest through an autorun CD, since we preferred retaining that feature. We experienced no similar problem with Virtual PC.

On more subjective matters, we give VMware a slight edge. We like its all-in-one interface. You can switch between guests by clicking on a tab and can change settings within the friendly confines of a single window. Virtual PC handles these tasks through a separate Console window. We also found VMware slightly more intuitive for moving between host and guest environments. Finally, while it wasn't important to us, if you intend to create multiple screenshots in a guest environment, VMware also has a slight edge in intrinsic capabilities. We prefer a third-party screen capture program running in the host to grab screenshots in a guest so the graphics survive in our primary environment if we abandon or roll back changes in a guest environment.

The bottom line: at this time, overall features are close to a dead heat. You must do your homework on which product better fits your specific needs in terms of supported OSes and other capabilities. And, as has been the case in the last year or so, expect competition between these two leading contenders to be red hot.

VMware Workstation 5

PROS: Supports a broad range of host and guest operating systems, as well as multiple processors in some guest environments.

CONS: Has difficulty with autorun CDs in guest environments.

Download at; $189 (packaged version $199)

Thumbnail, click for full-size image.
Figure 1. VMware's tabbed interface provides intuitive switching between guest environments--click for full-size image

Microsoft Virtual PC 2004

PROS: After acquisition by Microsoft, tight support for the company's recent and emerging OSes can be expected.

CONS: Is limited mostly to support for more recent Microsoft operating systems; no support for multiple processors; installing guests is slow.

Download at; $129

Thumbnail, click for full-size image.
Figure 2. Virtual PC's Console, which controls active guest environments and settings, runs in a separate window--click for full-size image

J.W. Olsen has written, edited, and served as freelance book project manager exclusively in technology publishing since 1990.

Return to the Windows DevCenter.