What OS to use, or build myself, to just show a browser after starting up?

"You want Google's Chrome OS once it comes out.

But you can do that with most Linux distributions... it's called Kiosk mode. You'll have to be careful about hardware."

"There have been a number of projects and ""howto""s that I've seen over the years that have this aim. http://kiosk.mozdevdotorg/ is the first Google hit for ""linux kiosk"" that looks up-to-date at first glance (Firefox 3.6 gets a mention in the Wiki) so that might be a good place to start.

Rolling your own Linux distro would be an interesting learning experience, and creating a browser based kiosk setup is a good example to try (as it'll be less complicated than creating a full desktop setup), though this is certainly not something I would recommend you do for a real use until you done it ""to play"" a couple of times - there is a lot to take in first time if your technical Linux experience is currently low so getting it right could take quite some time+effort."