Does your lapotop have an external monitior connection?
If your budget is $800 dollar then a xenarc would eat up half of that.
on boad sound
on board video
and everything else
ram-$60 (depends obviosly)
hard drive-u have
gps - delorme $100 with software or gps mice on Ebay like $60
power supply-opus 90watt-$160
xenarc 7in touch screen-$380
Everything With exeption to the RAM and gps sensor can be purchased on this site.