Sorry to resurrect an old post, but I think Eziriz's .NET Reactor works brilliantly.
In fact I use it myself for all my .net apps and apparently there is no existing tool out there that can decompile a program protected with .net reactor. More details can be found on there info page, http://www.eziriz.com/dotnet_reactor.htm. Test it out with the trial version and .net reflector and you can see for yourself.
