Configuring a PC around the minimum hardware requirements of an application or operating system is lot like agreeing to live in a basement apartment. Sure, it will work as a place to live -- if you don't mind damp and dim living conditions.

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 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.

For instance, Dell offers a Windows Vista Capable configuration that isn't capable of much, according to what Dell says about it on its Web site: "Great for ... Booting the Operating System, without running applications or games."

Dell recommends 2GB of system memory.

Microsoft may be using PCs loaded with 4GB of RAM for some of its customer demos; At least that's what Ann Westerheim, president of Ekaru, reports. A Microsoft representative recently demonstrated Vista on a system with 4GB of system memory to some of its customers, and the performance was so impressive that it drew some "ohs and ahs" from the audience, said Westerheim. The Westford, Mass.-based company provides technology services for small and mid-sized business.

Westerheim said that for her personal use she may configure a system with 2GB RAM, only because of the cost of loading 4GB on a laptop.

Mueez Deen, director of graphics memory and consumer DRAM at Samsung Electronics, also recommends 2GB of RAM, calling that amount the "optimal density for the complete Vista experience -- economically and technologically."