Parallels has introduced a new version of its virtualisation tool that lets users of Intel-based Mac systems access Windows applications.

Available immediately, Parallels Desktop 4.0 for Mac offers improved performance and easier access to some of its key features. It also adds 64-bit support plus the ability to make better use of multi-core processors.

As with the previous release, Desktop 4.0 supports Coherence, a feature that makes Windows applications appear to run natively on the Mac desktop, hiding the fact that they are actually inside a Windows virtual machine.

Users can now launch their most often accessed applications - Windows or OS X - from a Favourites bar. This also makes it easier to specify whether a particular file type opens with a Windows or a Mac application.

Users can choose whether a link in an email will open in a PC or Mac browser when clicked, according to Parallels.

"We have tried to make Desktop 4.0 a nicer place to be," said Russell Blackburn, Parallels country manager for the UK and Eire.

Desktop 4.0 adds support for up to eight processors, enabling users on systems such as Apple's Mac Pro to assign a virtual machine to a specific processor core. An adaptive hypervisor also balances resources between the virtual machines and the Mac desktop.

For Mac users worried about security, a new sliding control adjusts the level of integration between the virtual machines and OS X. By default, this is set for a high level of integration, allowing users to drag-and-drop files between environments, and letting applications in one environment access the file system of the other.

The new version also enables USB Flash disks to be accessed simultaneously by the PC and Mac environments, and remembers associations with particular USB devices so that plugging in a BlackBerry will always synchronise with the same one.

Other new features include the ability to search inside virtual machines using the Mac Spotlight tool, on-the-fly configuration of virtual machines, and Windows Notifications displayed on the Mac menu bar.

Parallels also bundles three Windows-based tools with the new version: Kaspersky Internet Security, Acronis True Image Home and Disk Director Suite.

The price of Parallels Desktop 4.0 for Mac remains unchanged at £49.99, while a new five-pack licence option has been added for £199. Those upgrading can get the new version for a discounted rate of £24.99 until the end of November, or for £31.99 thereafter.

Parallels also announced a tool for the iPhone that enables users to remotely control virtual machines. Described by Blackburn as the company's "first step towards integration with the iPhone and Mac", this lets a user start, stop, suspend and restart virtual machines remotely and is expected to appeal to administrators.