Visual Studio Express...free!
"You’ve helped make Visual Studio Express a runaway hit, and we’re proud to announce that in the five months since its launch, Express has been downloaded over 5 million times!"
5 million downloads? Wow. Dan also has links to some new starter kit content worth checking out.
"4. Can I use Express Editions for commercial use?
Yes, there are no licensing restrictions for applications built using the Express Editions."
And yet another thing to note. If you're looking for a free database to program against, then be reminded that you can download SQL Server 2005 Express Edition, again for free.