var slider=new Array();
slider[1]=new Object();
slider[1].min=10;
slider[1].max=750;
slider[1].val=100;
slider[1].onchange=setBoxValue;
slider[2]=new Object();
slider[2].min=5;
slider[2].max=60;
slider[2].val=30;
slider[2].onchange=setBoxValue;
slider[3]=new Object();
slider[3].min=0;
slider[3].max=50;
slider[3].val=10;
slider[3].onchange=setBoxValue;
function setBoxValue(val, box) {
    var b=document.getElementById('output'+box);
	val=Math.round(val*1)/1; /*you have a better way to do this!*/
	b.value=val;

var investment = 100;
var billing=document.getElementById('output1');
var minutes=document.getElementById('output2');
var forget=document.getElementById('output3');
var roi=document.getElementById('output4');
var total = (21.65*(billing.value)*(minutes.value)/120)+(173.2*(billing.value)*((forget.value)/100))-investment;
total = Math.round(total);
if(total<0)
	total=0;
roi.value= total;
}
/* here you set Output4 by:
#1 - hourly billing rate * time filling timesheets / 2 -- we don't eliminate all the time!
plus
#2 - hourly billing rate * how much forgotten work
1 and 2 need to be multiplied to be MONTHLY figures assuming 
a constant of 173.2 work hours every month.*/