I don't know of any, I don't do .Net at all. But I just wanted to point out that what you seem to be looking for is called an "obfuscator". Search ".Net Dll obfuscator", you will find plenty (free and not free).
Which edition of visual studio 2008 do you have? I think one of them includes a program called ".NET Obfuscator" or something like that.
EDIT: It's called Dotfuscator.
"Dotfuscator Community Edition does only very limited obfuscation and is included in Microsoft's Visual Studio. By registering for free, users can have the Enhanced Edition, which includes a better integration into Visual Studio, in addition to more obfuscation features. However, the Community Edition and the Enhanced Community Edition are designed for hobbyists, not professionals, because they lack most of the features. Furthermore, the license limits use to the work products of a single person"