Also, in GNS3 2.1.9, do use more than 5-6 2811 routers simultaneously on a mid-range laptop (i5, 8 GB RAM). Instead, use IOSv or IOU for larger topologies.
Download the appropriate .bin file from the Cisco Software Download page or an authorized educational source. Import to GNS3: cisco 2811 ios image gns3 download for 19