function attachImage()
{myIMG.style.left= event.x;
myIMG.style.top = event.y;}
window.document.onmousemove = attachImage;

<!--
　これは、ロールオーバーの機能です

function HpbImgPreload()
{ var appVer=parseInt(navigator.appVersion);
  var isNC=(document.layers && (appVer >= 4)); 
  var isIE=(document.all    && (appVer >= 4)); 
  if (isNC || isIE)
  { if (document.images)
    { var imgName = HpbImgPreload.arguments[0];
      var cnt;
      swImg[imgName] = new Array;
      for (cnt = 1; cnt < HpbImgPreload.arguments.length; cnt++)
      { swImg[imgName][HpbImgPreload.arguments[cnt]] = new Image();
        swImg[imgName][HpbImgPreload.arguments[cnt]].src = HpbImgPreload.arguments[cnt];
      }}}}
function HpbImgSwap(imgName, imgSrc)
{ var appVer=parseInt(navigator.appVersion);
  var isNC=(document.layers && (appVer >= 4)); 
  var isIE=(document.all    && (appVer >= 4)); 
  if (isNC || isIE)
  {if (document.images)
    { document.images[imgName].src = imgSrc;
    }}}
var swImg; swImg=new Array;

function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
//-->