I agree it makes for sense for an operating system (filesystem perhaps) to do this job. Unfortunately, Windows does not do it. Readyboost is merely an extra space for Superfetch to cache files, but this isnt persistent over reboots. So every time I boot, I have to retrain the cache, which is about as undesirable as a filesystem cache could be. If not sure if software like eBoostr solves this, but if anyone has a Windows alternative, much obliged.