aMSN is the best MSN IM in OS X. Period. Only Emesene (now ported to Mac too) can compete with it, but aMSN still the best option. I am saying this because I tried ALL other alternatives (Adium, Microsoft Messenger, err hmm mercury
) and they cannot be compared with aMSN.
So, look. Apple website has a download section for software. http://www.apple.com/downloads/
. aMSN have to be there! Just create a Apple ID (I have one) and submit it here https://adcweb.apple.com/downloads/
. A lot of people go there to download software. It has a quick access in Apple Menu -> Mac OS X Software
What do you think?