I'm curious to know what people prefer for virtualization options.  I'm talking about running another OS on your home machine (regardless of platform, Windows/Mac/Linux/FreeBSD/etc) -- and not for running any type of commercial or personal servers .. just the end-user desktop type virtualization.

For my response to the topic, I used to be a big fan of Parallels on the Mac.  The only thing I really used it for was running Windows so I could get to Quicken, because I greatly despise the Macintosh version of Quicken with all of the features it lacks.  A few months ago I tried VirtualBox and was quite impressed with what it could do, at a fraction of the price (free).