I discovered VirtualBox a few months ago and am now migrating to it away from VMWare Workstation. It's stable and performs well.
It also offers the Parallels-like feature which allows you to run application windows from your VM in your host desktop environment. This is very handy for doing cross-browser web app testing, where you can (for example) put a Win IE7 browser window right next to your Linux Firefox one to compare things side by side.
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I discovered VirtualBox a few months ago and am now migrating to it away from VMWare Workstation. It's stable and performs well.
It also offers the Parallels-like feature which allows you to run application windows from your VM in your host desktop environment. This is very handy for doing cross-browser web app testing, where you can (for example) put a Win IE7 browser window right next to your Linux Firefox one to compare things side by side.