Best zip code database?

Looking for a comprehensive zip code database that covers the entire world.

Zip codes, longitude, latitude (for radius searches), countries, cities, us states, etc… Been browsing the net for awhile, and hard to tell which one will be the best.

Need it for a website I am building, that will allow you to sign up and select where you live, and I will have a lot of users from around the world. Also need it for the search form, for searching countries, and zip code radius in the US and other countries if possible.

Any ideas?