But whatever. I am pleased to announce that I have finally completed the Half-Life 2 series, as it currently stands, including Portal.
Now seriously that shit was incredible. I'm absolutely distraught about missing out all these years. Episode Two was pretty emotional stuff, too.
I really liked how Episode One really pushed how Alyx is actually a person. I think the first moment I realised that this was more like a movie than anything else when Alyx got emotional over the Stalkers. That was pretty hard hitting. I don't think any other game has ever exemplified the intentional source of gamers' boners as a real person.
And goodness... the realism. It was astonishing how things reacted exactly as they should in the real world...
And I'll stop there because there's nothing I can say that wasn't said in 2004.

Ohh man now I wanna play the whole Half Life series over again. There was actually a time where I just couldn't get into the story or world or even the games itself. Man was I an idiot. After a few tries I was more immersed in the series then any game or movie I can even think of.
And here's to hoping something Half Life related gets announced at E3!

Yeah, Half-Life 2 was a really polished and a thought-trough experience. Good thing you didn't join the bashing that's starting to be popular for some reason :-)

Now you know the pain of the people who have had to wait for a new episode for 3 years.
This topic reminded me of this: http://xkcd.com/606/

Thanks for getting the nostalgia gears churning again.
Now I don't know whether to go back and play Deus Ex 1 again or play the Half Life 2 series again first.

I still haven't beaten HL2 or played the episodes. The first time I got to the bit where the Combine are blasting with some big turret thingy from atop a building (not long after you rescue Barney from the snipers). The second time I only got to the first bit in Nova Prospect where you set up the turrets.
In both cases my progress was halted by my rampant OCD forcing me to do bits over and over again because I was sure something glitched or otherwise didn't go right. Eventually my attention gets grabbed by something else and I stop playing the game for ages, and eventually decide I may as well start over. For the same reason, my attempts at replaying HL1 have generally been halted at that big diagonal lift with all the headcrabs raining down from above. But at least I've played through that several times and the expansions more than once.
My finances are approaching the point where I can get a decent new computer, so I might as well wait for that so I can play HL2 in its full glory. Kind of well timed considering they've added in the Xbox achievements.

Now I need to get HL1, I think. How much of the canon have I actually missed from not playing it? Don't spoil too much, just let me know if I've missed a huge connection or something.

What drives me crazy is thread titles that give me no idea what the thread is about. Didn't read. :P

And to add to that, should I be getting vanilla Half Life or Half Life Source?

The canon was, from the most part, mounted on top of the original game after Half-Life 2 came out... so don't expect any awesome revelations... or any realistic NPCs... :)
But in general, I can do nothing else but highly recommend the first game - a great FPS even by today's standards :)

Really, unless you get a boner over ragdoll physics and fancy water reflections, there's no need to buy Source, since it looks exactly the same as original HL, with the two exceptions above. You'll be better off getting half-life 1 Anthology with both expansions, which are pretty great as well

I vaguely recall people mentioning HL:Source had issues with player-height and jumps.
That being said, it depends on what you want. If you are playing for "plot", then I think either one will work. If gameplay, get the original and Opposing Forces. Opposing Forces was awesome :p

Did you get the Orange Box? As HL Source came bundled with it.

If you register the regular retail version of HL1 with Steam you get all kinds of bonuses, including all the expansions, CS, Day of Defeat, Team Fortress and a couple of others.

I don't have HL Source and I bought the Orange Box.