Just did some testing on this subject:
I'm using the abbreviation Mb (Megabit) here because I'm not exactly sure whether the K in Task Manager stands for KB (Kilobyte) or Kb (Kilobit), so I'll err in favour of SOE, and use Megabits 
EQ2 was using almost 450Mb in fullscreen mode, and switching to windowed mode did nothing for the memory usage.
When you minimize EQ2, the memory usage for it goes immediately to 25Mb, but then starts climbing up again.
Regardless of the state of EQ2 (minimized, restored in windowed mode) the game seems to increase memory usage at a rate of about 2Mb every 5 seconds. After reaching around 150Mb, the memory usage increase slows down, and seemed to even out at about 200Mb.
Exactly how EQ2 got to 450Mb when I was in fullscreen mode, I'm not sure.