I just checked my AIM version and I'm using 4.6. Granted, it's nowhere near the level of iChat as far as refinement is concerned, but for basic conversations it works fine. It also has a nice stock ticker function built in. The news ticker doesn't seem to function correctly anymore but everything else works without a problem.
Version 4.7 is compatible with OS 9 but is not recommended. There's an article on Low End Mac from 2004 that explains its shortcomings. It can be found here: http://lowendmac.com/archive/04/0402.html. The window size issue specifically pertains to clamshells as the resolution of the screens is relatively low.
Stick with 4.6 and you're in good shape as long as you have OS 9. I believe 4.3 is the last version that runs on OS 8.
Version 4.7 is compatible with OS 9 but is not recommended. There's an article on Low End Mac from 2004 that explains its shortcomings. It can be found here: http://lowendmac.com/archive/04/0402.html. The window size issue specifically pertains to clamshells as the resolution of the screens is relatively low.
Stick with 4.6 and you're in good shape as long as you have OS 9. I believe 4.3 is the last version that runs on OS 8.