Such may be the case for Windows Vista's minimum requirement of 512MB of RAM.

Microsoft's on-the-box minimum RAM requirement "really isn't realistic," according to David Short, an IBM consultant who works in its company's Global Services Divison. He says users should consider 4GB of RAM if they really want optimum Vista performance. With 512MB of RAM, Vista will deliver performance that's "sub-XP," he warned.

Short has been beta testing Vista for two years and was at the IBM-oriented Share user group conference in Tampa, Florida, last week discussing some of Vista's performance requirements. His XP system has 2GB of RAM, which he calls the "sweet spot" for that operating system, but on Vista, 4GB of RAM may be closer to its "Nirvana," he said.

That's due in part to Windows SuperFetch, which takes data from the hard drive, stores it in the available RAM and makes it readily accessible to the processor. SuperFetch depends a great deal on user predictability and takes snapshots of user activity. If SuperFetch determines that an application is launched at a particular time, it will have it loaded into the available RAM. With more RAM, there's more caching and better software response, said Short.

Hardware vendors, of course, will offer systems built on Microsoft's minimum hardware requirements called "Windows Vista Capable," configured with 512MB of system memory and a processor that is at least 800MHz. But their heart may not really be in it.