Apparently the IIS stack has changed in Server 2003. I've never noticed any issues with my ASP.NET apps, but in case you do, here's the full post: http://blogs.msdn.com/tom/archive/2008/03/31/stack-sizes-in-iis-affects-asp-net.aspx .
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Read the complete post at http://weblogs.asp.net/jgaylord/archive/2008/03/31/iis-stack-in-windows-server-2003.aspx