OK, if I'm reading this right, you have about 1.7 gB of memory being used in Task Manager.
Is that correct? I presume that you're getting your numbers from the Memory chart in the Performance tab?

If that is so, let's have a look at Resource Monitor's Memory tab. There's a link to Resource Monitor at the bottom of the Memory chart in the Performance tab of Task Manager - please click on it.
Then click on the Memory tab - That'll tell you what's running in the background and there's also a nice little chart that shows the usage of memory (and shows the hardware reserved stuff - more about that in the next paragraph).

In addition to several different types of memory being measured (see the other numbers in the Memory chart)., there's also a difference between memory used in physical memory - and that being used in virtual memory.
And, as TairikuOkami states, there's also address' that are reserved for physical devices
Finally, there's also other memory in the system - video, motherboard, CPU cache, etc and each one operates on it's own set of rules.

The reserving of address' also reserves the physical memory space that those drivers would occupy - but that leads us to a discussion of paged vs non-paged and I'm not prepared to delve into that mess!

If you have questions about this, then a screenshot of the Memory tab of Resource Monitor would help our discussion.