Get the Orange Box, HL2 Ep 1 and 2 are decent, portal is pretty fun, and TF2 makes it a bargain. It's also on sale sometimes- I got it for $18 online (and it was legit
). Plus, Half Life 2 can be gifted if you already have it, so it's not a waste to buy it again.
Plus, you can get
GoldenEye Source, still a bit rough around the edges but it's fun and you can't beat the price.