The best free game i can think of is "Alliance of valiant arms" (AvA). You need to download this ijji-reactor thingy: ijji - Where Gamers Unite!
It's a multiplayer ego-shooter with different game modes and back in the time I played it (about 2 mounth ago) there wern't many hackers (At least no aimbots etc..) I don't know what you call "high end", but this are the requierments (took them from wikipedia - http://en.wikipedia.org/wiki/Alliance_of_Valiant_Arms ):
System requirements Minimum
- CPU: Pentium 4 2.4Ghz
- RAM: 1GB
- GeForce 6600 or Radeon X600 GPU with 128MB GRAM Shader Model 2 Required
- 1.6 GB of Free Hard Drive Space
- Windows XP/Vista/7