Windows Memory mgmnt has it under its control. If you are looking at Task Manager, Available physical memory, and wondering why it is so big, possibly more than half your installed RAM, be assured that Windows and the processes running under it are using all the RAM they need. Available is memory that contains recently used processes and their data, ready for restart without an I/O operation to disk. Aw heck... read it here: http://support.microsoft.com/kb/312628
The Total commit Charge is the amount of memory actually being used at that moment, and it includes paged memory. You can't force Windows to use more RAM and not the page file because if you make too small a one, or none at all, Windows will quietly make one and not tell you about it.
As far as L2 cache goes, how much of it is used is up to your HAL. You know from your CPU spec sheet how much there is in the processor chip, you can see how much windows knows about from this key:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management]
"SecondLevelDataCache"=dword:00000000
That is a decimal dataword, zero implies 256KB.... you can set what your CPU has, in decimal KB. HAL might have it wrong.
Mine was not detected?, was originally set to minimum, so I set it to 6144. The sys seems happy; whether it made a difference, I don't know... I mean, cache size does make a difference [ http://www.tomshardware.com/reviews/cache-size-matter,1709-2.html] . Certainly other software knew it was there, even if Windows reported it wrongly. It is up to the processor programming itself, I guess.
eg, Sandra reports it correctly, and uses it in its tests. SIW reports it correctly.
[so JB, how do I phrase that lot "correctly"? Seriously...?]
