When using Dotfuscator to obfuscate your code you may find this tip helpful, since it automates the process of obfuscating.
Under Project Properties/Common Properties/Build Events and Post-build Event Command Line you can enter the following to automate the obfuscation process:
"C:\Program Files\PreEmptive Solutions\Dotfuscator Community Edition 1.1\dotfuscator.exe" /q ..\..\Dotfuscator.xml
copy ..\*.dll *.dll
This assumes that you have created a Dotfuscator project (Dotfuscator.xml) in your project and that ILdasm in your path and that the output of Dotfuscator is the bin folder of the project (change the copy statement if you have another output directory).
Now after a successful build Dotfuscator will obfuscate your DLL.