mobile + Gps device while driving.

I would like to know which would be the best combination, which mobile and which Gps software, to use as a gps device while driving outstation and unknown regions.

I dont want a dedicated gps device like tomtom, etc.

Please consider I am a complete novice at this gps utilities.

The mobile i prefer Nokia’s but i wouldn’t mid trying HTC etc, as long as the gps is quick and useful.

Feature Iam looking for

1. big screen
2. full touchscreen
3. quick gps and accurate.
4. inbuilt maps or can load maps. not GPRS maps from google. don’t want to spend on GPRS.
5. audio instructions – turn left in 20mtr – if possible.
6. Budget 20k

Suggestions ?