According to the company, the performance of Parallels is improved during OS startup and shutdown of the virtual machine.
This release includes improvements in resource usage, particularly CPU utilization. Users can now also allocate up to 2GB of RAM to an individual virtual machine. Windows Vista performs faster and more smoothly than in previous builds.
Here's more information about the Build 5160 update.
In case you have some ambiguity about which version and build you're running, the company provided a new knowledge base document with instructions on how to check.
It's a tough one:
1. Start Parallels Desktop for Mac. 2. From the Parallels Desktop menu, choose the About Parallels Desktop option. 3. The About Parallels Desktop window displays the build number and Parallels version.
The latest version is always available for download here.