The VPCS can simulate up to 9 PCs. You can ping/traceroute them, or ping/traceroute the other hosts/routers from the virtual PCs when you study the Cisco routers in the Dynamips. VPCS is not the traditional PC, it is just a program running on the Linux or Windows, and only few network commands can be used in it. But VPCS can give you a big hand when you study the Cisco devices in the Dynamips. VPCS can replace the routers or VMware boxes which are used as PCs in the Dynamips network.
Try VPCS, it can save your CPU/Memory. It is very small.
Now, VPCS can be run in udp or ether mode. In the udp mode, VPCS sends or receives the packets via udp. In the ether mode, via /dev/tap, not support on the Windows.