Действительно ли я могу изобразить использование памяти в виде графика для окон в кактусах?

short answer: Yes.

long answer: Install the windows SNMP server. From there on you will have to figure out which SNMP ID holds the windows memory. (cheat:

.1.3.6.1.2.1.25.2.3.1.5.6 – Total physical memory
.1.3.6.1.2.1.25.2.3.1.6.6 – Used physical memory
.1.3.6.1.2.1.25.2.3.1.6.6 – Total virtual memory ["virtual"="swap" in Windows lingo]
.1.3.6.1.2.1.25.2.3.1.6.6 – Used virtual memory)

After this: Profit!

Have a look at this site as well: http://www.netuality.ro/monitoring-windows-servers-with-snmp/tools/20060512/