Weird scrolling problem

I just finished www.LasikMemorial.com, but one nagging issue remains. Go to www.LasikMemorial.com/Home.htm  Use Lazarus for the password. I wrote a small javascript routine that displays pictures whenever one of the thumbnails is clicked (the "thumbnail" is just an image displayed as the background of an anchor tag). Problem is, this causes the browser to scroll back to the top of the document. How can I fix it?  Just worried about IE here, not Netscape or Opera.

function ShowPageImages(iLeft, iTop, iWidth, iHeight, stPicture)
  {
  stPicture="url(" + stPicture + ")" ;
  iLeft = iLeft + document.body.clientWidth/2-385+200+3
  document.getElementById("ShowImagesDIV").style.left=iLeft ;
  document.getElementById("ShowImagesDIV").style.top=iTop ;
  document.getElementById("ShowImagesDIV").style.width=iWidth ;
  document.getElementById("ShowImagesDIV").style.height=iHeight ;
  document.getElementById("ShowImagesDIV").style.background=stPicture;
  document.getElementById("ShowImagesDIV").style.visibility="visible" ;
  }