wanting to upgrade system

I have the pkg #6 2005 Prius and want to know what my options are. I would love to trade out the whole nav/stereo entertainment system for something like the Kenwood 5120, but can I assume that this is not possible because everything else is lumped in there on the prius (consumption/energy, maintenance log, etc etc)?

My primary problem is that I hate the nav system on the prius. i want something that uses Navteq mapping software and preferrably Garmin operating system (like Kenwood does). I would also like to add ipod. I already have xm radio, which was installed at Best Buy years ago. Unlike my external xm, I would like to integrate the xm and ipod so that they could be accessed from the screen, as if factory-installed. If I could get those things done (new nav, ipod, not lose the xm) I would be a happy camper.

What are my options here? thanks for any info!!

(ps/fyi, if you know of my last postings, I was going to sell the prius because i'd gotten a smart. family circumstances forced me to sell the smart and keep the prius instead.)