So I was interested in trying out "Miranda I-M" which looked from the screenshots (in default mode anyhow) to be a reasonably conventional-looking win32 GUI client and seems to be under active development judging by sourceforge stats.
Unfortunately after installation, which went pretty well, the program fails to start quite early on with this;
fixme:file:FindFirstChangeNotificationA this is not supported yet (non-trivial).
FWIW it runs fine here on Wine CVS, though being at work I didn't actually try to connect. Prefs window is b0rked like Trillians is, you can't switch tab pages. I suspect that's a bug in our treeview control. Some debugging would be required to make it work really well.