[Chaprnks]

The LargeSystemCache registry entry forces windows to allocate up to all but 4MB of system memory, that is system memory, not available RAM, to the file system cache. The remaining system memory is used for disk caching, though windows will allocate more memory if it is needed. In rough terms, system memory is where windows holds programs and data that are currently in use. This allows applications and files to be cached in RAM rather than stored on disk.

In short, it will only increase it by 4 megs, and most likely cause problems.