There are two paths towards CCNA certification:
The two-exam path: 640-822 (ICND 1) and 640-816 (ICND 2). Typically, you pass the ICND 1 exam (you become a CCENT then) and then you pass the ICND 2 exam and you become a CCNA. Each exam costs about 125 US dollars.
The one-exam path: 640-802. This is the "one-shot" composite exam. If you pass it, you become a CCNA. This exam costs about 250 US dollars.
People usually suggest the one-exam path if you have some decent networking experience, or the two-exam path if you are more of a newbie. But this isn't really important, just go with whatever path feels right for you.
In addition to the excellent GNS3 emulator that Peter suggested, you will probably need Packet Tracer, a free simulator from Cisco. Normally GNS3 would be more than enough but unfortunately it can't emulate Cisco switches (it offers only simple, unmanaged switches).
In contrast to what PP is saying, I don't believe it's difficult to pass the CCNA exam without access to real Cisco equipment. This is more of a requirement as you go further up the chain of Cisco certifications (e.g. CCNP). Real switches and routers definitely give you better insight but GNS3 + Packet Tracer will suffice for the CCNA exam. Having said that, you can get free access to real Cisco equipment over at the Packetlife Lab (haven't tried it myself).
You can find forums, advice etc at the Cisco Learning Network.