It would be nice for the 770 to get support for PAN but I highly doubt it. I think windows mobile is going to incorporate DUN back into it before we can get support for PAN. I downloaded my WM6 upgrade at http://wmblack.info/

I think the XDA-Developers site has alot of good info but i think its mostly for HTC devices. You got to find some hacjed rom for your phone. ALso I had problems trying to pair my WM5 device with my 770 on 2006 edition. I never actually tried using WM5 with the 2007HE I think it might be able to work. If you can pair the 770 and your phone on WM5, then open up the phone utility and your phone shows up as one of the devices then it should work.