edit: too slow. i guess this is just to add to what mickz said....
i think you are really mistaken as to what a carpc does, and needs.
this depends on your hardware, and the way the bios is setup. the processor selection has little to do with this. there are fast booting boards and slow booting boards.. i can get a atom board that boots faster then a i7 board, and the other way around.
2. overall speed:
while there is a noticable difference between a atom processor and pentium, there really isn't much difference between a pentium and i7 (i have 4 pc's-- a atom board home pc, a mobile pentium laptop, a 775 socket pentium in-car, and a i7 gaming rig)
but again, the way the that the system is setup and configured affects the speed more then the processor. with the right tweaks, i can make a atom board feel just as fast as a pentium..
the difference between a pentium and a i7 is in very-very-heavy processing. like gaming, and autocad..
doing things like surfing the web, listening to music, gps, etc is not enough to even get the pentium to break a sweat. i doubt you would be able to tell a difference just browsing web pages between a pentium and a i7.
the processor is overkill.
the 8gb ram is complete overkill.
i run 2gb in car, and it is plenty for my heavier-then-average carpc use(i use the carpc for realtime audio manipulation).
also, if you ever plan to use hibernate, the smaller the amount of ram, the better. remember that when you hibernate, the pc needs to write all the data from the ram into the hdd. that can take quite a while even with 2gb..
slot load type is the best for car use, as there is a possiblity that a tray-load drive could break while loading a cd on a bumpy road.
i am not familiar with that gps receiver, though, i believe that as long as it outputs nmea(sp?) data, then it should be useable with any mapping program. if it outputs it's own version of data, then it is pretty much useless. the bu353 is the most popular receiver here, and has been verified to work with all the available gps programs.