Like others have said, it really depends on the game. Counter-Strike has very low requirements since when Half-Life first came out the fastest processors were only around 700 mhz.
Aside from the hardware your major hurdle is getting enough bandwidth. The solution: find someone in a college dorm network. At the UW dorms the bandwidth per room is amazing (both upload and download) so I know a couple of people who host game servers and my ping to them is usually between 16-30
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