Why are you whining about kissing WON goodbye?
If you goto Valves site and take a look at what their trying to do with steam and some of the things coming out for it you wouldn't be whining.
Such as, they're getting rid of the idea that you have to be online all the time, they're working on a patch so that you have to log in to download the content (obviously) and then you can disconnect from steam and play it Single Player or on a LAN.
Also, HL2 is going to support its self, it doesn't need steam. First clue to this is that, they said it will run out of box and steam is not required. The second clue would be that Its going to run on Linux out of box, steam isn't supported on linux, not yet anyway.
This is what I would suggest, If you have a decent computer and your internet connection isn't very slow (faster then 56K) you should get steam. You can download just the installer which is like 500k and install only the mods you want to play, so you don't need their 'chached' versions or anything.
I've actually had better connections with steam . . . I've had less lag (mostly because everyone playing has broadband) and I've come to enjoy the interface much more then WONs (Mostly because my sound doesn't go away if Half-Life gets minimized).
But yes Steam does suck up some resources, saying its a hog is exaturating.
Right now My system is running steam heres the memory usage:
Steam 4,224 K
To keep this in a realm of comparison Mozilla is running at 24,000K and Internet Explorer is going at 24,304K
So it's not too bad, its about the same as AIM. Once you're playing a game it uses the same amount of recources as WON version would use.
The only thing that you can whine about regarding steam is if you want to develope maps. I found the easiest way is to create a mod folder under half-life, it will show up as a 3rd party mod. The only problem is, when you configure Hammer, you have to manually move the bsp and you can't have hammer moving it for you, because it just doesn't work.
If you want wad files goto nemesis tools theres a program called 
 GCF Scape, its very good. It allows you to exctract anything you want from the GCF files, however you can't write anything so you can't make your own or anything like that.
Steam isn't as bad as everyone is saying, they're just biased, steam didn't work when I first put it on either, but that was when it first came out and it sucked ass when it came out, it's incredibly stable now. However I think Gabe trips his fat ass over the power cable every now and then lol.
Anyway, why don't you try both out? You already know what WON is like, try using steam.
Just keep in mind, if you want to play Sven Co-op 3.0 online you have to use steam, because of the half-life version.