My Mac-laptop’s been running Leopard ( OSX ) for quite some time. For the times when I wanted to use a windows app I had installed both VMWare fusion and Parallels Desktop ver 3 . Both of these did get the job done , but that came at a price ( $49 to $75)
A few days back I tried out a FREE virtualization application from Sun called VirtualBox.
Besides being free, Virtualbox was amazingly easy to install and very very functional. I did have to go through a full Windows XP install , but I was up and running immediately. This was a lot better than say VMware fusion , where I had to struggle to install the applications that allowed my mouse to roam freely between the host OS and the guest OS . Also on linux where I have been using it for some time ..its very stable.
While Virtualbox is free , as of version 2.1.3 , it does lack some of the features that Parallels and VMWare provide , like drag and drop , and it does not support the function key for Mac osX ( read this Ars technica review). Also virtualbox is improving at quite a pace and you never know any feature you are missing might already be in the newest version .
All in all its a great way to test your apps on windows while runing linux for free!