You can still play Oblivion on older hardware.
http://www.oldblivion.com/
As for Stalker, that one might be okay, but it really looks bad without the lighting on, which will indeed need newer hardware.
Oldblivion crashed all the time when I tried it, and it worked but made the game *slower* on my cousin's computer, but, I guess, it helps someone.
I got a $40 AGP card from TigerDirect a couple months ago, and I absolutely love playing Portal and Oblivion. I also play Half-Life 2 every once in a while, and I play a few other awesome-looking games. If I want to play Morrowind, though, I have it on my modified Xbox, well, I have a modified Morrowind on there. (It's a ghetto version of Oblivion.)