I've see this question too many times (from customers and on forums) and I think this is the time to clear this fact.
During the first presentation of Dynamics NAV 5.0 (the future release of the Microsoft Navision ERP system) Microsoft said that it will be the first application of its ERP family that will run on its upcoming Windows Vista operating system.
The natural question out after this sentence was: will Dynamics NAV 5.0 require Windows Vista to run (or at least on the server side)?
The answer is NO... Dynamics NAV 5.0 will be able to run on Windows Vista (and under Vista it can use all the new features of the OS, such as security, visual effects etc.) but this is absolutely not a requirement. You will be able to run Dynamics NAV 5.0 on the actual Windows systems, the only new requirement will be the .NET Framework 