An intro to Virtual PC for Mac

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Joined: 02/12/2009

[Editor's Note 4/2007: things have changed a lot since this article was written. Apple's new Intel chip-based computers and "Bootcamp" allow Mac users to run the Windows OS directly on their Mac. And other third-party apps add functionality much like Virtual PC.]

The general consensus regarding the "MHz Myth" is that Mac processor speeds are equivalent to PC processors that are 2-3 times higher. So, a 1GHz Mac is comparable to a 2-3 GHz PC, due to the fact that the processor chips are completely different breeds. This ratio is a huge generalization because there are a dozen major factors and hundreds of minor factors that affect any comparison. It is indeed comparing Apples and Oranges. But keep the 1-to-2 (or 3) ratio in mind when people compare Mac and PC prices.

Virtual PC is an application (formerly made by Connectix, recently bought by Microsoft) that runs any number of OSes. The Mac version can run WinXP, 2000, NT, 98, 95, 32, dos, OS/2 and various *nix OSes like Linux. It saves each OS as one large file that, when launched, acts like a PC boot drive. You can run multiple simultaneous OSes, network them, and drag-and-drop between them and the Mac OS. You can save the running OS as a "saved state" for quick access without having to boot it up. Pretty cool. The PC version of Virtual PC can do all this too. (But it can't be used to run the Mac OS on a PC. Sorry.)

VPC requires a lot of processor power to do its thing. The emulation overhead causes it to run the emulated OS much slower. Each version of VPC purports to run faster than the last, but that is always followed by a lot of fine print. It depends heavily on the version of the Mac OS that you use and the version of the guest PC OS (98, XP etc).

Quantitative speed comparisons are extremely hard to do since there are so many interrelated factors: Mac OS version, Virtual PC version, Guest OS version, Guest OS service packs, and more.

Basically, using the same hardware for comparison, I have found that older guest PC OSes (95, 98) run faster than newer ones (XP) because they need less processor power. Similarly, running Virtual PC under Mac OS 9 is faster than running it under OS X because OS X demands more of the same hardware. But, at least one report says that Win2000 and XP perform better when VPC runs in OS X than when VPC runs in OS 9. But I have not seen that in my tests.

There are two exceptions to the general trend of "older is better." The first is that Virtual PC itself has become more efficient with each new release (4, 5, 6, etc). [Edit 1/2005: VPC 7 has now been released, which takes advantage of the G5 processor.] The second exception is that OS X has become more efficient in many ways from version 10.0 to 10.3 and thus some apps run faster in later versions of OS X. But this is hard to quantify.

The bottom line is that you will need a very fast Mac to use VPC, and even then you will only be able to use it for tasks that are not too demanding. Virtual PC is fine for basic web browser compatibility testing, FlashROM updates to devices, and the occasional PC-only application. For many Mac users, though, the most demanding tasks such as Audio/Video editing and Photoshop are better done on the Mac anyway.

( Click here to price Virtual PC at )

Here's Microsoft's comparison of the different flavors of VPC for Mac:

Joined: 02/12/2009

Note that VPC versions before 7 apparently won't run on a G5:

Any VPC user should tune up their PC OS to run as efficiently as possible:
(Start with the articles that show you how to adjust settings to free up resources. Skip the ones that talk about buying software to speed things up.)

There are some good tips to squeeze better performance out of the old VPC 5 here:

Here are some related articles with user reports on Virtual PC speed tests, comparing versions:,2125,65241,00.html

Also see this thread on using VPC with the Rhapsody music service. It has a few tips at the end about adjusting VPC's process priority: