Welcome to th forum. It depends on how you want to receive
dtv signals.
If you plan on watching TV while not driving. Any converter (like the Insignia or DTVPal) will connect to your in-dash as long as their is an RCA or RF input on your in-dash unit. With a normal digital-to-converter box though, you will not be able to receive
dtv signals if you're going faster than 5-7MPH.
If you want the TV to be viewable while driving, there's a new "mobile" format coming out at the beginning of 2010 called
ATSC-M/H. It'll be the only way to watch over-the-air television while moving at speeds 7 MPH and above.