Parallels Desktop for Mac was the first kid on the block to support virtualisation of other PC operating systems on Mac OS X. However, in the past fortnight, I’ve found out that:

1. Parallels allocates just a tad too many unnecessary Quartz windows¹, which causes the Mac OS X WindowServer to start going bonkers on larger monitors. I’ve personally seen the right half of a TextEdit window disappear, and Safari not being able to create a new window while Parallels is running, even with no VM running. (I’ve started a discussion about this on the Parallels forums.)
2. Parallels does evil things with your Windows XP Boot Camp partition, such as replace your ntoskrnl.exe and hal.dll file and rewriting the crucial boot.ini file. This causes some rather hard-to-diagnose problems with some low-level software, such as MacDrive, a fine product that’s pretty much essential for my Boot Camp use. Personally, I’d rather not use a virtualisation program that decides to screw around with my operating system kernel, hardware abstraction layer, and boot settings, thank you very much.

VMware Fusion does none of these dumbass things, and provides the same, simple drag’n’drop support and shared folders to share files between Windows XP and Mac OS X. I concur with stuffonfire about VMware Fusion Beta 3: even in beta, it’s a lot better than Parallels so far. Far better host operating system performance, better network support, hard disk snapshots (albeit not with Boot Camp), and DirectX 8.1 support to boot. (A good friend o’ mine reckons that 3D Studio runs faster in VMware Fusion on his Core 2 Duo MacBook Pro than it does natively on his dedicated Athlon 64 Windows machine. Nice.) The only major feature missing from VMware Fusion is Coherence, and I can live without that. It’s very cool, but hardly necessary.

Oh yeah, and since VMWare Fusion in beta right now, it’s free as well. Go get it.

¹ Strictly speaking, allocating a ton of Quartz windows is Qt’s fault, not Parallels’s fault. Google Earth has the same problem. However, I don’t really care if it’s Qt’s fault, considering that it simply means running Parallels at all (even with no VM open) renders my machine unstable.