Well, during my search for a good Windows Twitter client, a friend recommended MetroTwit to me.
Didn't sound very good, but I went to their site to take a look, I had been using either TweetDeck or Seesmic for a while and hated them.
I needed something that was quick, responsive, and could run in the system tray and give me notifications. I have become so obsessed with Push notifications on my iPod that I basically think everything should work that way.
So I downloaded MetroTwit, installed it, went through some errors with .NET 4 (btw I hate .NET with a passion). Finally got it installed after a couple minutes of random tinkering.
On launch, I was greeted with an appealing simple UI, with subtle animations and a nice color scheme. Immediately I got my account set up, and logged it.
Well, I just got to say that MetroTwit is the best darn Twitter client for Windows I've ever used. Sure, it lacks a few features, like multiple account sign in, but they'll be added soon I read.
Here's a screenshot:
So if you're looking for a really awesome Twitter client for Windows, I consider MetroTwit to be the best there is for the platform.
Download it at their site: http://www.metrotwit.com/