Like Zone of the Enders 2 at some of the bosses fights, Metal Gear Solid series is probably too althrough I have pc version soo I dunno really

, Shadow of the Collossus if you want smoother animation can be a killer too(through easily playable at worser cpu with a bit choppy animation;P), Armored Core.
Others probably know more of demanding titles, I'm mainly interested in RPG's which are usually the easiest games to emulate(the most demanding RPG I tried till now was Valkyrie Profile 2 which should run with full speed at 3.1ghz i3). If you have a list of titles you "must" replay on your future pc, maybe just ask about them, it's easier than listing it.
There were also some topics about demanding games already, but it's not like there are soo many of them. i3 around 3ghz should really be enough for most less troublesome games by default, with some speedhacks with alot more, and your GPU will be above average and enough to enjoy nice graphics(as long as the game is playable without glitches to begin with).