With portal on steam, if I move to another computer, will I still have portal, in the not installed section? Also, if I uninstall it to re-install it because something is wrong, will it still be in my steam account? Just in case if my computer crashes again, so that I won't have to buy portal again, just install steam, and get portal for free again.

If you uninstall it, as long as you can still connect to Steam on the username you used to buy Portal, you can download and install it again for nothing, (also as long as Valve still has the game available for download).

and yes you can goto another house, or computer, and it will be there. though you will have to install it.

Yep, gotta love the new age of totally awesome digital distribution.

However, your personal files are not stored on Steam, not yet. So no savegames or acces to hard levels.

SteamCloud is a feature that is currently in development and should support this, but it is far from complete right now. Your achievements are stored on your account, however, and will still be there.

Yeah. You can install using the one Steam Account on as many Computer's you want, and you can uninstall and reinstall infinite times...though why you would want to uninstall portal is beyond me...

I've actually installed Steam on a computer at my school once, I needed Portal and the Hammer-tool for a special project. The only problem was the computer's specs: it was very new, but its specs dated from before the stone age. Well, those computers aren't ment to play games anyway, but at least they could support Portal on lowest graphics. Hooray for Source's low minimum system requirements!

So, yeah, I had to log in on my account. Could simply install and play everything. I simply love digital destribution, though it's way faster to just install it from the disc.