I normally don't care much for deathmatch games, especially after EA raped the crap out of Battlefield 2, but TF2 so far has to be the most balanced game I've played and I love it for that. Valva is also really good at keeping the game good and clean of exploits and cheats (Exploits in Halo 2 ruined the game).

The Orange Box is probably one of the best games purchases out there. I say it's totally worth it. I didn't give a damn about Half-Life or TF2 for a while, but then my roomy bought me the Box and I very much enjoy them all now.

GET ORANGE BOX
NOW

Half-life and its sequels and expansions are brilliant (both in storytelling and game-play), and Portal is just ungodly good.

i got my dad the orange box for christmas and all he played was the old half lifes and portal (once lol)

I would seriously pay just to play portal by itself, it's just so unique and fun. You can probably beat it in a day but it has replay value.
personally I've never played half-life or tf2 (SHAAAAME) but I want to :<

oh and happy birthday :}