Old versions of itunes 4.1.7, 4.9, 5.0.1

I would like to update my version of itunes as much as possible. I have system 10.1.5 (and also 9.2.2 available) and if possible would like a version of itunes that I can get podcasts with. Please suggest the proper version, and more importantly, tell me where I can find the older versions of itunes to download (I have only been able to ind 4.1.7 in downloads... I will use it if that's as far as my system can upgrade to but I think I need 4.9 for podcasts)