HELP with CCNA cisco 3640 routers 2

[greythoundny]

Hi all I am starting to study so one day I can get my CCNA Cert. I currently have 4 cisco 3640 routers and I wanted to know which IOS I should use on them to study with, here is a list of the ones I have:
c3640-ik9o3s-mz.124-3 ---- IP/FW/IDS PLUS IPSEC 3DES
c3640-jk9s-mz.124-16 ------ ENTERPRISE PLUS IPSEC 3DES
c3640-is-mz.124-16 --------- IP PLUS
c3640-i-mz.124-16 ---------- IP
c3640-ik9s-mz.124-16 ------ IP PLUS IPSEC 3DES

Thank You in advance !!!

 

[burtsbees]

c3640-ik9o3s-mz.124-3 ---- IP/FW/IDS PLUS IPSEC 3DES
c3640-jk9s-mz.124-16 ------ ENTERPRISE PLUS IPSEC 3DES

Those are the best. Two routers can have each one.

Burt