Hard drive is going to limit your options. Do you have an iPod? That is the best thing to have then it is easy to update as well.

Personally I would stick with the big brands, Pioneer and Alpine both have some very nice double DIN units with different options. I have an Alpine unit in mine and love it. The AVIC is a top unit and had I had a larger budget I would have gone for one of them, although I don't need sat nav so went for one without that.

Adam