UPDATE [04 OCT 2013] - Removed the links because 2010 trials are no longer available.
To put these all in one place, here are the links to the Visual Studio 2010 trial editions and .NET Framework 4 downloads on the Microsoft Download Center.
.NET Framework 4
See: .net Downloads
Visual Studio 2010 Express Editions
See: Visual Studio Express
Visual Studio 2010 Trial Editions
Broken links, per usual... MS really needs to get their website together. Over the years I've found it to be one of the most buggy and broken sites I use.