I played Deus Ex originally with these specs:
Voodoo 3 3000 (16MB of RAM I believe)
either 64 or 128 MB of RAM (I can't remember)
Creative Soundblaster Live!
I played at 1024x768 and the game ran smooth as silk.
/goes and installs Deus Ex on his crappy old 800mhz lappy xD
Honestly i thought it wouldnt handle it, i stand corrected. More fun me on the train to work.
Ironsung....everyone has a fave old game mate thats why you get so many responses
Another one i havent seen mentioned is Grim Fandago....Monkey Island with more dead people.