http://www.microsoft.com/Express/ - Express IDE's are lighter weight free IDE's meant for students or hobbyists. They do not include all the bells and whistles but should be sufficent to learn how to code anything.
The compiler for .Net is distributed with the framework so you could actually code in Notepad (Although I'd just get the free IDE)
Also if your a new company (less then 3 years old), have less then 1 million in revenue a year and are privatley you should checkout http://www.microsoft.com/BizSpark/. With Bizspark you can get a full featured license of MSDN with VSTS. You only pay $100.00 when you leave the program.
Had we known about this eight months ago we'd have saved ourselves tons of cash.