Query...I almost did not open your post, because "Quriey" looked like a trade name..
Yes--you can tell the Xandros installer to take the "K" partition (except that partitions don't have letters in the Linux world.)
To be on the safe side, be sure you know what drive (in Linux-speak) it is goin to install to. If you have one disk, it will likely show up as hda1 (Windows C) and hda2 (Linux). The installer should also tell you that Windows is on one of the partitions.
I don't know why the router would care what OS you are running. Mine is configured from a web browser--I could be on a Mac for all it knows.