Why a little memory is used in the first place by Vista explains another question asked lately about the SuperFetch now seen in Vista superceding the PreFetch seen with XP when that was first introduced there namely a form of memory management that preloads the most commonly used programs into a standby mode seeing them load faster. I remember reading on this when Vista was first being introduced.
Under the same title, SuperFetch, the MS information goes as follows:
"Windows SuperFetch enables programs and files to load much faster than they would on Windows XP–based PCs.
When you're not actively using your computer, background tasks—including automatic backup programs and antivirus scans—run when they will least disturb you. These background tasks can take up system memory space that your programs had been using. On Windows XP–based PCs, this can slow progress to a crawl when you attempt to resume work.
SuperFetch monitors which applications you use the most and preloads these into your system memory so they'll be ready when you need them. Windows Vista also runs background programs, like disk defragmenting and Windows Defender, at low priority so that they can do their job but your work always comes first."
http://www.microsoft.com/windows/windows-vista/features/superfetch.aspx
This is one of the main reasons you even see upto 50% taken up out of a 2gb total.
