For a while, at least, I've set aside the Powerbook during the day, and am exclusively a Windows guy while at work. Mostly it's not bad; the annoyances that have always been a part of Windows are only slightly worsened by the past year's association with OS X (and I've continued to use Windows a lot during that time, anyway). But there's one thing I'm having a very hard time living without: iChat.

It's amazing how subtle user interface design is, and how important it is. When I first saw iChat, the only thing that was noticeably different about it was the little speech bubbles, and I saw them as useless eye candy. I was sure the first thing I would do when I got iChat would be to turn them off. And it was the first thing I did -- but I almost immediately turned them on again. The bubbles, with their different colors and different alignment (your own icon is on the right, the other person's on the left) makes it much easier to distinguish different parts of the conversation.

Now that I'm using AIM again, I'm noticing all kinds of things that (like a comfy Eames chair) you don't appreciate until they're gone:

• Automatic logging of all of your chats. I'm a guy who uses his email archive as an extended memory, and one of the things that was initially troubling about instant messaging was its transience. iChat made that a non-issue.
• Every-five-minutes-or-so timestamps in the chat window to help track the flow of time in the conversation.
• Sorting the buddy list by status (online and active at the top, then idle, then away, then offline). The list of people I could actually chat with right away nearly always fit on the screen in iChat; now I almost always have to scroll. And while using iChat, I never once missed the categories that AIM allows you to sort your buddy list into.
• Status message displayed in the buddy list. Many Mac users have begun using iChat as an awareness tool, updating their status messages frequently to indicate where they are or what they're doing. I miss that, not just because it helps me feel connected to my friends, but it lets me know when it's a good time to interrupt.
• Buddy icons displayed in the buddy list. A few friends change their buddy icons frequently, and meaningfully. (Like when James counted down the days to Panther's release with screenshots from the "time remaining" display on Apple's home page.) It's fun to watch, and now I feel like I might be missing something.
• Display of real names instead of AIM screen names. Who are these people in my buddy list? I have no clue who some of them are. I'll have to check my Mac address book sometime to put names with IDs again. (Display of real names has another advantage: concealment of my friends' AIM ids, which many people like to keep private.)
• Much easier (and more elegant) sending of files between users.

Those are mostly in order of priority. If anyone knows of a Windows-based AIM-compatible chat program that supports most of these features, especially the ones near the top of the list, please let me know.