I've used the Garmins before and really liked them, but I just use my Droid now for navigation. I've used a TomTom once and it was alright, but it was an older version so i'm not sure what they're like now.
as for install, check this out. A couple good ideas in there. I liked the one that had it mounted to the left side and had it hard wired in.
http://www.camaro5.com/forums/showth...ight=gps+mount