Hey Spick,
Day of Defeat has the best graphics for a Half Life mod. It's a multiplayer, Counter-Strike-like game where you play as British, Americans or Germans. You chose your class and you kill your enemies. It's either Capture-The-Flag, Team Deathmatch or King of the Hill type games.
DoD has the following:
- Nice weapon deign with cool sounds
- Excellent radio
- The ability to throw back grenades
- Stamina
- Great targeting system
- Fun
I don't play half life nor multiplayer but you might try...

The DOD site has also free image hosting :0).