Question about Steam and multiple machines

Hey everyone,
I'm buying my wife a laptop for Christmas and I was wondering if its possible to share games purchased on Steam on multiple PCs but only running one at a time. So, let's say I'm playing some Team Fortress 2 over Steam on my PC and she wants to jump on her laptop and play Plants vs. Zombies on her laptop at the same time. Can we even do this? Is it even possible to authenticate two instances of Steam simultaneously?

Nope. When you log on one, it logs you out of the other.

I guess you could work around it by logging one on in offline mode, then moving to the other.

Yea, the only way to do this is by going into offline mode for one of the PC's.

You can also have her load up the single player game and then load up Steam yourself second. I played Left 4 Dead while my girlfriend played Plants Vs. Zombies this way. Whoever logs on second automatically boots the first. If the first is only playing a game like Peggle or Plants Vs. Zombies, this shouldn't matter and the game won't close. Just be careful.

1. Get all the games she wants to play loaded.
2. File -> Go Offline.
3. She enjoys games the same time as you while on the same account.