We use AIM at work and regularly have to save our IMs. Last I knew, iChat's formatting didn't save sn's or IM send time. Also, while pretty, iChat's interface is about 'bubbles!' and 'graphics!' and all I need is text.
Don't know Adium and would simply prefer help with this issue not a you-should-be-using xyz back and forth. Thanks
iChat saves all that information, just more efficiently (for example, only the time every 5 minutes, not the exact time to the second for every message), and you can also turn off the bubbles. iChat saves chats into the iChats folder in your Documents folder, it isn't hard to find at all, and the logs can be organized by name, time, etc just like anything else in the Finder. Adium too, although I find Adium a little clunky especially in the IM window area (yeah its tabbed, but it doesn't look quite right).
AIM for Mac is a really horrible piece of crap software that hasn't been updated in years and years because AOL realizes they don't have a competitive product for Mac, so thats why the suggestions.