Net impact would be zero, because the ice displaces its fluid weight in water.
However, if the glaciers are partially supported by land, then they could raise sea level.
It's not only Antarctica, but Greenland and Canada Glaciers and ice caps are now melting away too. Here's a April 4th, 2005 report from recent research conducted by NASA scientists.
http://www.blackanthem.com/scitech/2005040402.html
Here's some more data on post 51-54 ? about Antarctic Glaciers & maps.
"Earthquakes in Antarctica"
http://www.freerepublic.com/f-news/1349516/posts?q=1&&page=1