If you are building a reusable web part that you would like to sell or give away you should look into localizing your web part. The localization support is great with .NET 2.0, using resource files, and there are tons of built-in functionality for this. If you are creating an Editor Part for you web part, then your life is pretty easy, just use the standard techniques. But if you are using the approach by tagging the properties of your web part with the Personalizable attributes, then you are out of luck.