For serious chatting though, I recommend a heavyweight client like Pidgin (formerly called Gaim before AOL's lawyers had their way). Pidgin supports over a dozen instant messaging (IM) protocols such as XMPP, AIM, ICQ, MSN, and Yahoo messenger. The Google clients support only XMPP. Pidgin runs on Windows and Linux so if you have a Mac you'll have to use something else. The best I've found so far on the Mac is Adium.
BTW, the Gmail storage counter is up to 5.2 GB now.