Currently I use a plugin for VS2005 that I found on CodeProject (http://www.codeproject.com/KB/cs/Code_convert_add-in.aspx); it use an external service (http://www.carlosag.net/Tools/CodeTranslator/) to perform translation.
Occasionally, when I'm offline, I use a converter tool (http://www.kamalpatel.net/ConvertCSharp2VB.aspx).
