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For the most part, the actual base functionality of each device is the same as a low end device -- A switch is still a switch, but one from Cisco will have VLANs with layer 3 filtering, whereas you may not have dealt with VLANs and the like before. That doesn't mean that the Cisco concept of a VLAN is any different than the RFC or IEEE's concept of a VLAN, so you could learn about them elsewhere and take that knowledge with you and apply base concepts to Cisco gear.
I'd actually recommend picking up a book (I've seen many "how to build a... " in regards to Cisco networking), and using that as a learning tool and a reference. The Cisco IOS and peculiarities for each device will only come with experience. I have many times seen junior admins tear their hair out trying to figure out why the 1720 router won't "wri t" from the "conf" section of IOS, whereas the PIXes will. :)
Little things that are only learned through experience. Go with your gut, learn the most you can, and "feel the flow" of the network ;)
MM