Mac OS X only: The original Windows-on-Mac virtualization software Parallels—which we've used to run Windows and Mac apps side-by-side, set Windows programs as defaults on a Mac, and boot our Boot Camp partition from inside OS X—has just updated to Parallels 4. The good news: Parallels 4 boasts 50% faster performance than Parallels 3, while promising to use 15-30% fewer resources. Other new features include:

• SmartMount: Access removable storage devices from both Windows and Mac at the same time.
• SmartConnect: Instantly connect USB devices to Windows or Mac based on your set preferences
• iPhone Remote Control App: Start up and shut down Windows, Linux or any other VM directly from your iPhone.
• Modality View Mode: View Windows in a scaled view on your desktop for transparent viewing.
• Clips Tool: Share several Windows or Mac screen captures to the Mac?s clipboard to paste into Apple Mail, iChat or Pages.

The only downside: Parallels 3 users will need to pony up $40 for an upgrade. If you're totally new to Parallels, a full license will set you back $80. We haven't been able to compare the latest Parallels with its biggest competition, VMware Fusion, yet, but if you've tried both, let's hear if you've noticed performance differences in the comments.