Completed HL2 last night, was quite suprised when it ended, only realised I'd done it when the credits started to roll!
I'm slightly ashamed to admit that I never completed the original Half-life! I blame that on my impatence as a teenager.
Wikipedia has good sections on Half-life and Half-life 2 which explain the plot to those idiots like me who never completed it!
Was a pretty amazing game, even on my laptop. It's a pretty high spec laptop, but I'd like more RAM (only 512MB(!!) at the mo) and that's very expensive to put in. I've also found that the GeForce GO laptop graphics card I have is good, but not quite good enough. If only I had the space and the cash for a nice high end desktop......
Oh well, back to the much neglected GTA: San Andreas now :-)