I am planning to build a network attached storage (NAS) server.

Is there a way to cache frequently acccessed files from the remote storage automatically on the local PC?

(I am not looking for a way to sync whole folders like rsync, but rather something that automatically and transparently caches the last accessed 50 gb of files.)

Ideally I am searching for something that caches writes as well as reads, since only one pc will be accessing the server (and one day of lost changes if the local cache is damaged would be acceptable)

I looked into windows offline files, but as far as I could tell this requires manual interaction to disconnect the server or go into offline mode in order to use the cache.

The server would probably be running Linux or freeNAS, the pc runs Windows xp, but could be upgraded to 7 if required.