Mechwarrior 4 is now free if you like FPSes. You don't even have to pirate it. http://www.mektek.net/projects/mw4/
pretty strong it can play mw2 and n64 games perfectly if that will give you an idea i really dont know it has 4gb ram and a quad core processor thats all i know
Okay. PS3-gen. If you like point n' click adventures Sam and Max Seasons one to three and Monkey Island 1 and 2 remastered are MUSTS. And strong bad's cool game for a attractive people too. If you want to try before you pirate, each episode has a free demo, except for sam and max s1e4, which is the WHOLE GAME free.
neverwinter nights knights of the old republic 1 and 2 morrowind oblivion dunno, what games do you prefer?
What do you think of these? Mass Effect 2 Assassins greed 2 Crysis, Crysis Warhead , Mafia 2 With the info you provided ( 4 GB RAM and a Quad core CPU) the CPU can play the games how they work depends on your Graphics card you've got.