A 1921 would be fine for CCNA subjects, but you don't really need hardware for router simulations. GNS3 does an impeccable job at that for virtually free. So long as you understand and can configure OSPF, EIGRP, and static routes you have a lot of routing subjects covered for the CCNA level subjects. Two catalyst 3750's would get you a lot more mileage, they can do a lot of the basic routing functions and will help you with switching. There aren't any great switching simulators out there yet.
