Free Windows emulator for Intel-based Mac

Now why would I want such a thing given that there already is Boot Camp? Very simple: I might be using OS X as my primary environment but occasionally have to try out things using specific Windows software. For example, I might want to check whether the XHTML and JavaScript code in the presentation tier of a web application work in Internet Explorer without shutting down and rebooting back-and-forth between OS X and Windows all the time.

So how do I do this for free (the emulation part, that is, because Windows itself is not free)? Even our MSDN Academic Alliance site license doesn't help in this case because Virtual PC does not work on Intel-based Macs. Luckily, I stumbled across this list of emulators, which includes a reference to Q, a Cocoa port of the open-source emulator QEMU. Q supports multiple guest PCs and takes advantage of OS X's advanced technical capabilities.

Even though Q is still in alpha status, it is well-documented and includes a detailed tutorial for installing Windows XP SP2. I had no trouble performing this installation and running IE. Keyboard focus can be a bit quirky: it seems to think that a modifier key is stuck. If this problem doesn't go away by minimizing and restoring IE, it sending Ctrl-Alt-Del to the guest PC and invoking the task manager's "run command" menu item without actually running anything seems to take care of it.

In summary, Q gets this particular job done for me, and I think it is emerging as a serious competitor to the commercial emulators.