How to download an older version of iTunes?

I'm trying to jailbreak my iPhone 2g with whited00r. And to what I'm noticing, it looks like it should work, but each time I try, it says there was an error on line 1604. And I recently updated to the newest iTunes, but I think I need an older one for it to work. When I try to download an older version, it will download, but I can't get it to open for whatever reason. It says the library.lib file will not work because it was created with a newer version. Is there any other way to get an older version again? What am I missing?

No: Unfortunately itunes are clever this way: Once you have upgraded to itunes 11 you can't go backwards to an old version:

The new format for your library is no longer compatible with older versions:

And this will not assist in jailbreaking the ipod