So, does that mean if you go mobile (ie laptop or LAN party), you'd always take your CDs/DVDs with you or what are you going to imply?
Personally,
I crack all of my games if they require a disk on the drive to run because I cannot be bothered to reach for the disk just because I'm currently feeling like playing this game or the other.
Suffice to say it would be insane both because of the weight and the risk to damage/lose them to carry the disks around with my laptop.
Also, STEAM is the first time ever I bought games online so naturally I own a lot of games on disks.
D2D and the like simply isn't for me and when I have the chance to buy retail, I do so.
You can play around 30 games provided you bought them of course
If you still have the CD key of some older Valve games you can enable them in STEAM.
Of course this does not keep you from installing the game from your retail disks and playing them in SP mode as you did before so you don't lose anything (apart from the fact that once a game is bound to your account it cannot be removed again so you couldn't sell games - which is about the biggest negative side of STEAM IMO!)
Since STEAM is first and foremost a distribution system
step 1 and first part of 2 are no longer needed.
If you're going to play MP via inet anyway, there's no difference using STEAM or the conventional retail version actually.
With the difference that STEAM will automatically patch your game to the latest version so you don't have to hunt for patches any more.
I agree, though, that it is annoying you still have to "verify" your retail game online, even if you only want to play SP (ie HL