Parallels has released a fifth build of its Windows virtualisation software, ushering in USB support and a new feature to make it easier to share documents between both Mac and Windows operating systems.

The software lets users run multiple operating systems (such as Linux and Windows) simultaneously with Mac OS X. Unlike Apple's Boot Camp software, Parallels lets Intel Macs run multiple operating systems at once, so it does not require a reboot to each system.

The beta - Parallels Workstation for Mac OS X Beta5 - is available now for free download. "If you're already a beta tester, you can just install Beta5 on top of your current version. You will not have to rebuild your virtual machines," the company explains.

Additional improvements in the release include: support for dynamic screen resolutions; better keyboard mapping and mouse response; improvements in sound support; and problems when waking the primary OS from sleep have been repaired.

The software also introduces a new "transition cube" animation for moving to and from full-screen mode. The company has published a video showing this feature in action.

Some instabilites that caused occasional kernel panics have been resolved.