Be sure you’re upgrading for the right reasons. It’s very easy to get caught up in the visual minutia of these games where anisotropic filtering and so on are selling points, but at the end of the day none of that stuff makes the game more enjoyable to play. A dog of a game remains a dog no matter how good it looks.
After playing the cream of new PC releases this Christmas I still had much more fun with Orbz http://www.21-6.com/orbz.asp and unlike most PC games it runs on both OS X, Windows and Linux.
As for HL 2, chances are it might just show up at E3 this May..again. Valve really screwed both themselves and their partners this time around. Their publishers results for the past couple of quarters have been dire since all that projected HL revenue never happened.