If you have maintenance, the upgrade to VSphere 4.1 is free and you will benefit from:
- NFS Performance Enhancements. Networking performance for NFS has been optimized to improve throughput and reduce CPU usage.
- Storage Performance Statistics. vSphere 4.1 offers enhanced visibility into storage throughput and latency of hosts and virtual machines, and aids in troubleshooting storage performance issues. NFS statistics are now available in vCenter Server performance charts, as well as esxtop. New VMDK and datastore statistics are included.
- vMotion Enhancements. In vSphere 4.1, vMotion enhancements significantly improve the performance of migrations, with support for more simultaneous virtual machine migrations and faster individual virtual machine migrations.
- Memory Compression. In the event memory becomes constrained on a host there is now another method vSphere can utilize to prevent swapping memory to disk. This can help prevent burst memory utilization from causing performance degradation.
- USB Device Passthrough. Have USB license key dongles attached via IP-to-USB converters? You will now be able to remove those devices and plug your keys directly into your hosts while still preserving the ability to vMotion your guests using the USB device.
One note on requirements, vCenter 4.1 which is now a 64-bit only application and must be installed on a 64-bit operating system (2003 or 2008). vCenter cannot be installed on a domain controller and the recommended practice from VMware is to install vCenter as a VM.