I do as well...UltraVNC and I fireup the carputer using my alarm remote...
I have a USB Wi-Fi adapter with a 7dB gain, external antenna. Perfect...
Aside from already having 10,000 karaoke tracks on board for passengers to sing to, my car music collection consists of 95% music videos, all of which are downloaded from the internet. Having an always on, high-speed mobile internet connection has helped me out in that respect.
Nevertheless, I do use wifi at times, but only for war driving. As far as the antenna is concerned, it's from a fixed WRT54G Linksys router disguised on the rear package tray.
I use wireless, have a buffalo something or rather.
And the RR version of Upd8 to sync up.
Ever since I switched to having a large hard drive for my music, updating it wirelessly requires me to run back and forth from the house to the car... kind of a hassle. I had to turn on my laptop, run to the car, start up the carpc, run back inside, run synctoy on my laptop, finish, run back to the car, shut down the carpc. This especially sucks in the winter if I didnt park my car in the garage.
I'm waiting for parts to build a Windows Home Server machine, so hopefully that should simplify things a bit. Then I can just run Synctoy from the car before driving off to school/work.
Wireless router directly over my car in the carport. When I pull in, car connects, StreetDeck links to the home network and syncs music library.
My opinion is my own.