My favorite tool for the virtual machine environment, VMware, is released to version 5.0 now. One of the enhancenments on the new version I am interested in is improved multi-virtual machine performance. Besides this, US$189 for one copy actually is not bad.
What's New in Version 5
Whether you're a long-time power user of VMware Workstation or a beginning user who is just learning what you can do with virtual machines, the new features in VMware Workstation 5 extend its capabilities and make it easier to use.
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Improved Multi-Virtual Machine Performance
Workstation 5 includes significant improvements in memory utilization when virtual machines are used concurrently. This allows you to efficiently run multiple virtual machines with much less total memory.
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see what's new in VMware version 5 here