How to create new points in a existent map in batch

I'm just starting with GIS, and i would like to know if any existing
open source GIS can help me with this task:

First i need a world map, with city names, border, coastlines and so
on. I found some servers that have that data, like
http://viz.globe.gov/viz-bin/wmt.cgi

Now, i want to add some places, which aren't in the map yet, for
example a museum. I do have the (x, y) coordinates for a list of
places, and i want to import them into a map, but i don't know::

- What open source GIS can load a map like the one that offers
http://viz.globe.gov/viz-bin/wmt.cgi
- Which data format to use to import the data (exists an XML format?),
and how to import it

Thanks in advance,