Also, I think I need to be sensitive of how I say this, but a great option for someone with a considerably out of date computer would be certain programs that allow you to play old console(nes/snes/ps1/n64 are all possible) games on said computer. don't forget that option is available and 100% free.
That's true. Not long ago I started playing mike tyson punchout for free on the internet. I loved that game when I was a kid.
Simcity 2000 Sim Ant Sim Tower FreeSpace 2 TIE Fighter WarCraft II Diablo Civilization 2 Vampire: Bloodlines Doom I & II So many...
Grim Fandango, not rpg but still fun as hell Baldur's Gate 1 and 2 as others have said Fallout 1 and 2 Deus Ex 1
duke nukem sucks and always sucked. quake/unreal shit all over that crappy game. its a little newer, but play dungeon siege 2. i have all the baldurs gate disks in my case, but there is no way i still have the CD key
If you're not necessarily looking for old games, just games that can run on a crappy PC, try out TF2 and other valve games, they don't run too bad. But my favorite "old game" is Age of Empires 2.