I'd go with RoadRunner, Developed in VB6.
Nice touchscreen interface, completely skinnable (i reccomend the DigitalFX 2.0 skin) and works great with iGuidance, streets and trips, and others.
Voice recognition I havent looked in to , but i bet someone has.
Fast startup can be done. Maybe not as fast as the TomTom but quick. I have my system here booting windows in 13 seconds. Add a bit for the BIOS POST and whatnot, and its decently fast. For shutdown, most systems just go in to hibernate, or standby. Check out the M2 ATX power supply in the mp3car.com store.
Streamlined way to copy content.. Theres a cool app to copy media from CDs and thumbdrives when inserted in to the computer, and im sure theres ways to sync music between your car and home computers. I just havent looked in to it yet, but will in the not too distant future.
Ipod integration is done and works great =]
Just my two cents. The sources for RoadRunner are great as well, and got me started on developing my RRCam program =]