actually, save your money my friend. for what you will be expected to know on the CCNA exam, you can use a program called PacketTracer. Cisco’s Netacademy offers it for download and it’s a wonderful tool that will not just allow you to practice switch and router programming, but also network design, topology and implementation of cross platform services such as EIGRP, RIP and OSPF based networks working together. Just for starters that is. give it a shot before you go out and spend money.
Another great tool is dynamips. Search for the GNS3+Dynamips package and you can run REAL IOS