The IM feature for Skype is terrible. The interface for it sucks and running multiple convos sucks. I have zero interest in video or voice chatting. That is why I hated Skype. I used it for less then an hour before I got rid of it and downloaded Trillian. Hell you are talking to the same guy who still uses AIM. I also don't own a SmartPhone, I use my cheap 20 dollar prepaid phone.
I assume you didn't bother enabling separate chat windows for multiple convos?