Is google talk popular?
I don't know anyone using it.
use GoogleTalk (Gtalk). I got so sick and tired of all the stupid addon crap from Yahoo! IM and MSN Messenger, like ugly emoticons, buzzes, long animations, advertisements, and all manner of other bloat. Gtalk is lean, mean, and sticks to the basics. I don't know how many resources other IM clients use these days because I haven't used anything else in a couple of years, but Gtalk is currently using only 5MB of RAM.
I love Gtalk. Also, I have it set up to archives all of my conversations to my Gmail account. Then in two years when I remember having a conversation with someone about a particular topic, but I can't remember when, I just search from within Gmail and usually find it pretty quickly.