I have found this other gadget for viewing memory (Resource Monitor) allocation in Windows 7, and so addition to by last post I will add the following observations, it would appear that the superfetch feature uses "standby" memeory, which is not shown in the task manager memory.
Since upgrading I have seen this standby memory grow up to the full size of the spare RAM, which is good, I want as much info cached as possible so when I load stuff it doesn't have to come from hard drive.
Rightly or wrongly I have switched off the page file, and the pc is running perfectly well, with no hangs. . only problem is that you notice how slow you internet is when the rest of the pc is running well!
So I would say that more even though you RAM usage is showing on 25% in use, its worth adding more RAM, as more "standby" can be used to cache, stuff you might use.
All very technical again for which I apologize.
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