Need aftermarket Nav/Entertainment System for 04 Hummer H2?

I recently purchased an 04 Hummer H2. This was the first year the H2 came with a navigation system. The newer navs and entertainment systems are far superior. Could someone please recommend a resource that could help me upgrade my system? ThanksNeed aftermarket Nav/Entertainment System for 04 Hummer H2?I'm not sure if you mean a new factory upgrade or an aftermarket. If you want aftermarket go with the pioneer AVIC-Z1. it has a 30 gig hard drive for navigation(no nav disc) and for storing your favorite music.can do blue tooth hands free, direct I-pod interface, satellite radio with traffic nav, back up camera, voice activated controls,and plays DVDs. with the right adapters you can retain bose, on star and steering wheel controls.