using Obfuscator alone is not going to help. You need to understand what obfuscator work and then code accordingly so that it would become hard for someone to decompile your code.
Few months back I read an excellent article which went into much details .. the link to the article is lost my unorganized bookmarks ..
I am sorry my comment isn't that helpful .. but I just wanted to let you know .. its more than just using software to obfuscate your code.