jleslie053,
The 800 series are fine since they have the Cisco IOS and CLI on them you can get lots of practice with the IOS commands.
The 2 disadvantage I can think of is that they do not have serial interfaces - the sims on the CCNA exam mimic 2501 routers with 2 serial interfaces and 1 Ethernet interface - might not hurt to have 2 2501s and an 871 in the mix!
Also - the default IOS on the 871 for example does not do OSPF and the CCNA does cover OSPF in a single area as well as RIP and EIGRP! You will need a setup that is able to do all three.
Also it would be hard to do Frame Relay on the 800 without serial interfaces.
Just some thoughts!
E.A. Broda
CCNA, CCDA, CCAI, Network +