I always thought satellite was spelled with one T. Just a suggestion.
PC Install: 85%
Car PC: Revo-Sys X300 Double Din: 1.3GHz Pentium
Software install and setup: 35%
Entertainment Package: 85%
machine locked down.
As far as remote hacking goes, on windows it doesn't matter if you are logged in as admin or not. What matters is how you have your machine locked down. The only thing that really matters that much is viruses. If you have a severely limited account then that might stop *some* viruses. If you log in as admin, have AV software, and keep it up to date, you are OK. Ditto with the Spyware crap.
Where it can be bad to login as admin is in a X-windows setup on a *NIX box. Besides stupid stuff like accidentally deleting files, etc. there was an X-Windows vulnerability a long time ago that if you were currently logged in as admin, a hacker could take over and control your X-windows session and gain root access. I don't use X-Windows, but I would assum that that vuln is long fixed. If not, setting up TCP Wrappers on your ports will fix that vuln too.
Now, that all being said... for a CarPC odds are that not going to be connecting to the internet all the time, or downloading virus-filled illegal software. If you do web browser on your CarPC, it is also likley that you will be visiting a limited number of known sites. It's not like you are gonna be browsing and driving a lot.
If you use a HORM setup, you can get all the viruses you want. Just reboot and they are gone.