Which to choose?

I need to know which game to get for it's multiplayer.

UT3

Gears of War

Quake Wars

Which has the most people playing, and can it support a old system, AGP 8x?

AGP card? sounds pretty old. you might want to take a test at System Requirements Lab before you buy anything.

Anyways, this is pretty tough. UT3 was considered a disappointment. You might even want to choose UT2004 instead. Dunno about Quake Wars, but it doesn't sound too popular. Gears might be the best choice. I'm just unsure about the community on the PC version