Obfuscating is not a real protection.
If you have a .NET Exe file there is a FAR better solution.
I use Themida and can tell that it works very well.
The only drawback of Themida is that it cannot protect .NET Dlls.
(It also protects C++ code in Exe and DLLs)
Themida is by far cheaper than the here mentioned obfuscators and is the best in anti piracy protection on the market. It creates a virtual machine were critical parts of your code are run and runs several threads that detect manipulation or breakpoints set by a cracker. It converts the .NET Exe into something that Reflector does not even recognize as a .NET assembly anymore.
Please read the detailed description on their website:
http://www.oreans.com/themida_features.php
