How easy and risky is it to transfer a Steam account from one PC to another?

Someone I know is without a computer right now and is using someone else’s. I’d like to give that person a few games on Steam. I’d also like that person to be able to keep playing those games after having switched to another PC, which would require transferring the Steam account to another PC.
I’d like to know how involved that is and what the risks are. I once transferred my account to a friend’s PC and nothing bad happened but that might have been a fluke. I’d really like the games I gift to stay as gifts and not become unavailable because Steam suspects foul play where there is none.

It is extremely easy - very much like accessing the 'Durp from a different computer, except that large files will be re-downloaded to the new computer. The process is as safe as your password is.

You just log into the Steam client in the new PC, I thought. It’s not even a “transfer”.

Doesn’t Steam red flag such transfers? Could Steam block the account if it’s accessed by two PCs in a short period of time (though not at exactly the same time)?

The may / will send an email confirmation, with a code to punch into steam to validate her ID.

It’s very easy, and entirely risk free. When you sign into Steam from a computer, Steam’s servers log that computer as a unique ID. So long as you continue to log in from that computer, everything’s cool. If you try to sign into Steam from a new computer, Steam automatically sends a code to whatever email account they have on file for you. Type the code into Steam, and from then on, you can access your account freely from either computer.

There’s no apparent limit on how frequently you can access Steam from different computers in one day. I went back to school last year, and got in the habit of installing Steam on the school computers between classes (and, occasionally, during some of the more boring ones). I ended up access Steam on as many as three different computers (not counting my home PC) in one day, and never got any grief from it from Valve. Neither does there seem to be any hard limit on how many different computers can be associated with your account. The computers at school would restore themselves to their original state every time they were rebooted, which Steam read as installing on a whole new computer. I’ve probably had as many as thirty different PCs associated with my Steam account, and aside from entering the email code each time, the process was entirely transparent. You don’t need to manage which computers are associated with your account at all.

Can you install the same game on multiple computers, or does it track that you uninstalled a game from one machine before you load it on another?

You can have the same game installed on as many computers as you want, although only one person may be logged into Steam under your account at a time.

You could probably get around that to some extent by installing on one computer and setting that computer to offline mode. I’ve never had reason to try though.

I’ve switched computers with my Steam account once, and it went very smoothly. I just had to log in on the new machine and download my games again. Queuing up four or five big downloads (I had problems trying to arrange more concurrent downloads) before going to bed kept this inconvenience to a minimum. As far as I know, there are only problems if people try to sign in to the same account on multiple machines simultaneously. One person using their own account on many machines serially should encounter no problems.

Nope. Steam only lets you log into one computer at a time. Logging into a second computer will log you out of the first, but there’s no other repercussions.

You don’t even need to download the games - just copy the game onto an external hard drive and paste it into the right folder on the new computer. This has worked with every Steam game I’ve tried it on.

You can also always put one computer into offline mode. There’s some games where you can play LAN multiplayer with only one steam account by putting one of the computers into offline mode.