I am a c# developer and most of my friends are much smarter than me, and they laugh at me and start to swear at me in smalltalk. I want to learn this so that I might better be insulted at their insults... and maybe learn a thing or two in the process.
So, what is the best place to start with regard to smalltalk in a windows environment?
The best current free Smalltalk is probably Squeak. This currently out-performs its near relative Pharo, at least on my ancient box, but you should really take a look at both of them.
The big problem with Smalltalk is that there are no really high-quality text books. There's a list of free ones here, but I couldn't recommend any of them strongly. If you decide to use Squeak, take a look at Squeak By Example, which isn't too bad.
There is a nice new website called The World of Smalltalk http://www.world.st, where you can find a simple yet comprehensible entry to the Smalltalk world, from introduction and documentation to the blogs, mailing lists, dialects and frameworks.
On Windows there are Win-only Dolphin Smalltalk, free cross-platform Squeak and Pharo, and commercial VisualWorks.
Good luck!
Squeak, like Neil Butterworth said, and hang out on squeak-dev. The beginners mailing list's a good place to ask questions.
So, what is the best place to start with regard to smalltalk in a windows environment?
Perhaps it would be best to leverage your familiarity with MS Windows - "Dolphin Smalltalk X6 is an object-oriented development environment for Microsoft Windows™."
Try the "free for personal/educational use" "Community Edition" of Dolphin Smalltalk.
To get started, I would recommend a seaside one-click image. Seaside is a most interesting web-framework and the image is based on Pharo. There are a number of screencasts available. The authors of SQB expanded the book and adapted it to Pharo at Pharo-By-Example. They have a high-volume development mailing list and a users list. For seaside you'd want the users list. Seaside also has a book and the tutorials by James Foster which I'd recommend you to look first at.
I do not find significant speed differences between Pharo and Squeak, but Pharo is much cleaner due to its developer focus. Squeak contains a lot more interesting tidbits.
If you find the one-click image (there is also one available in a Squeak version) not fast enough, the introduction of the cog vm will improve performance by a factor two or so.
On Windows you should make sure that your anti-virus software does not try to verify the changes file each time it is written, or your Smalltalk environment gets to be very slow.
For learning a lot (not recommended to start with) you should take a look at the Moose one-click image and the book by Doru.
As Janko said, Pharo and Squeak are good Smalltalk implementations to start with, but I would also like to add Cincom's WebVelocity which is a bit different. It is a VisualWorks/Seaside based Smalltalk IDE in the browser.
Whichever environment you pick to start playing with, don't forget to check out Stéphane Ducasse's collection of FREE (and LEGAL) Smalltalk books: Free Smalltalk Books