Crysis and FarCry were watershed games. No computer could run it well at launch and it was used as a benchmark for years, A GT530 should be able to run it. Roughly equivalent to the 8800 GTS I tried it with for the first time. I could run the base game (though the GPU ran way too hot for my liking), but that mod was a whole other level of polygon counts. I never really played Crysis itself, there is a modification for Crysis Warhead that turned it into a MechWarrior title (Living Legends, still active, some of the devs from CryTek work on it). Still one of the better gameplay experiences in that genre. I had played all the Mechwarriors, 2, 3, and 4, and 4 Mercenaries (Mechwarrior 5 Mercenaries came out like 2 years ago no, something like a 15 year gap (Though Mechwarrior Online is out there, not quite the same)
CryEngine is still kind of a gold standard for high requirements PC gaming.
XP era, well, I was big into multiplayer first person shooters. So Quake III, Quake III Team Arena, Unreal Tournament, Unreal Tournament III (never really cared for 2k3 or 2k4). But those games don't have campaigns. HalfLife and CounterStrike. Battlefield series, I have more hours in 1942 then I care to admit, that is actually now free to play on Origin though there is basically no anti-cheat system. Call of Duty, Call of Duty 2, Modern Warfare. There would have been the limited releases of Halo on the PC that I never got into.
Sid Meier's Pirates was always a fun distraction. Tron 2.0 has a good story.
Command & Conquer Generals, Red Alert 3, Sins of Solar Empire, WarCraft III (and the original DOTA mod). Never did play it, but Homeworld was a big title for RTS.
I was big into Eve Online at the time, and that MMO is still out there.