Can anyone explain to me how I can tell exactly what processes are using how much memory in Windows XP? It is a little trickier in Vista and Windows 7 because stuff gets pre-loaded into RAM but in XP the reported physical memory used should be what is actually being used by currently loaded stuff.

If I use SysInternals process explorer there are lots of different memory stats listed such as Working Set, Private Bytes, Virtual Size.

Right now my 4GB XP 64bit system says it is using 60.8% of physical memory. If I look at working set numbers, nothing adds up even close to that. If I add up all the Private Bytes sections listed I get 1,664,000K RAM used when I should have something like 2,552,404K used to get my 60%.

So where is that extra 1GB of RAM hiding? If I look at the virtual size, that is reporting almost 8GB so that isn't telling me the current actively used RAM either.

Is there another tool that can tell me where my RAM is hiding and what is using it?

Jeff.