I'm of the opinion that it would be an overall better idea to use your shiny new iPhone with AT&T, but hey I'm not the one deciding for everybody am I.

If you've decided that a hacked iPhone to work outside the World AT&T is just your cup'of'tea then you'll be pleased to know that a new GUI unlocking tool is now available from the iPhone Dev Team. If you must have, a quick search should yield satisfying results.