Have item template field for circle as linkbutton and itemtemplate field for your values as Label and in gridView_RowDataBound check the value of the label if the value is greater that 0 then enable the link and if the value is 0 then disable the link.
Following example explains the words-----
protected void gridView1_RowDataBound(object sender,GridViewRowEventArgs e)
{
Label lblValue= (Label)e.Row.FindControl("lblValue1");
LinkButton lnkBtn= (LinkButton)e.Row.findControl("lnkBtn");
if(Convert.ToInt32(lvlValue.Text)>0)
{
lnkBtn.enabled=true;
}
else
{
lnkBtn.enabled=false;
}
}
I guess it helps you....