Since my switch to Ubuntu, I've been loving every minute of my experience with it. I've already learned to define the applications that can make my life easier and pinpointed how to rearrange my desktop so that it saves me time and effort when moving around.
I love the fact too that my sisters are slowly progressing with using Ubuntu as our primary OS. Of course, I do plan to have a Windows XP for dual boot just in case we need it, but I'm not gonna tell them about that plan.. hihihi.. 
Well, one thing though, that I find myself missing is a good Google Talk interface for my chatting needs. I actually abhor the fact that I do have to keep more than one IM interface all the time because, though I find the icons cute, while they lounge in my taskbar, its still annoying while it eats up precious memory and taskbar space. lolz! For sure, my sisters miss their good old Yahoo! Messenger where they usually chat to death (when I'm not around of course).
I've been used to having Gaim around, especially at work. I use it to communicate with the people in the office and send files too. Though, I'm finding it hard to like because I feel that the interface is quite dull and the icons are boring! Lately, Gaim has been replaced with Pidgin.
A pidgin is a new language which develops in situations where speakers of different languages need to communicate but don't share a common language.Defined here
Pidgin is an instant messaging program for Windows, Linux, BSD, and other Unixes. You can talk to your friends using AIM, ICQ, Jabber/XMPP, MSN Messenger, Yahoo!, Bonjour, Gadu-Gadu, IRC, Novell GroupWise Messenger, QQ, Lotus Sametime, SILC, SIMPLE, and Zephyr.Pidgin can log in to multiple accounts on multiple IM networks simultaneously. This means that you can be chatting with friends on AIM, talking to a friend on Yahoo Messenger, and sitting in an IRC channel all at the same time.
From Pidgin
Prounouned as pigeon, Pidgin gives me the power to put all my contacts under this one interface.
I can talk to my friends in Google, MSN and YM in this one interface! It has many plugins too that I find useful. Some them are Buddy Pounce, Buddy Notes, History, Conversation Colors, Message Notification, Plugin Themes, Psychic Mode, and a lot more! Right now, all I ever can think about is how to make Pidgin talk to Skype.. hmmm.. and, of course, I'm gonna get myself involved with them! I think I'd like to contribute a good set of icons too! 
Though, there are still some drawbacks to their feature list, like, I think their file sending is still quite buggy, its still the best IM to use for it can connect you to all your friends regardless of network. 
I used to like the fine web version of IM'ing, which is Meebo. It kinda does the same. I also used to have their widget sit here in my blog site, but I find it frustrating because I cannot move around working and switching to my browser each time a friend buzzes me. Imagine having around 30+ tabs open in your Firefox, and you can't even notice the changing tab title that displays your friend's chat window and you're not wearing your headset to hear the minute clinking sound of a friend's buzz. Aahh.. well, those were the days. With my Pidgin, at least, I can set it to blink each time I receive a buzz. That is kinda useful when I'm not wearing my headset to hear its chat buzz sound.
At least give Pidgin a try. 
There is a version available for Windows, and for Linux. If you're using Ubuntu, see this reference for installing Pidgin.