Itunes for 10.5.8

Wanting to re-load itunes on my desktop MAC as I deleted it due to space issues I have now resolved, now I cant download the latest itunes because it requires Mac OS X 10.6 or above and I only have 10.5.8 I have tried updating my software but it says everything us up to date......... do I need to upgrade to 10.6 (how do I do this??) or do I need an older version of itunes (how do I find this???)? 😕