form.submit中控制。。。。
html>
script language=javascript>
function dosubmit(){
window.open('first.php?var1='+window.form.var1.value+'&var2='+window.form.var2.value);
window.open('second.php?var1='+window.form.var1.value+'&var2='+window.form.var2.value);
return false;
}
/script>
form name=form onsubmit="return dosubmit();">
input type=text name=var1>br>
input type=text name=var2>
br>input type=submit>/form>