Connectix's Virtual PC 3.0.3 is a mature PC emulator now available with Red Hat Linux 6.1 preinstalled and preconfigured. For those who don't want to run just any form of Linux--for example, one that runs natively on a Power Mac--but who need to run an x86-based Linux, this combo offers interesting possibilities.
As Power Macs become increasingly powerful and have more and more RAM at their disposal, using software to emulate hardware has become progressively more practical. Emulators for old hardware--arcade games, old personal computers, and the like--abound. But the horsepower in a contemporary PowerPC processor is also substantial enough to emulate software designed to run on contemporary hardware, such as a Wintel PC.
It makes sense for Connectix to have chosen Red Hat Linux as its offering: it's the most recognizable brand name in Linux. The big question is, what exactly do users of this Virtual PC version get by running emulated Linux rather than a PowerPC-native version? In a word, applications. As Linux's importance in the server world grows, an increasing number of companies are providing software that runs on x86-based Linux.
So, why is this relevant in the Mac universe? Virtual PC offers unparalleled configuration and testing options that allow you to thoroughly test and debug a given configuration before actually implementing it on a real PC. With Virtual PC, you can set up as many virtual disks as hard-disk space permits. And, if you make an irrevocable mistake, all you need to do is create a new virtual disk and continue; it's much easier than reformatting and reinstalling an OS on a real PC.
One area where Linux hasn't yet made major inroads is on the desktop. This is due in large part to a lack of productivity applications. While loads of useful development-oriented and server software is available for Linux, desktop applications are still lacking. This, unsurprisingly, is also the Achilles' heel of Virtual PC with Red Hat Linux. Linux's GUI is based on a collection of software called XFree86, an open-source version of the venerable X Windows system originally from MIT. At its best, X Windows is not known for its sprightly performance; when running under emulation, this weakness is even more apparent.
However, if your intention is to use Virtual PC with Red Hat Linux for testing x86-based Linux software, odds are that you intend to try out server software rather than graphical applications. In this scenario, Virtual PC's core PC emulator is plenty fast enough.