You really don't need much in AA when everything is surrounded in thick black outlines.
And just that is completely wrong! You don't need AA in a reealistic-graphics-game in HD. But in Borderlands, there are all the thick black lines that should look like painted - but they don't due to the lack of Anti Aliasing! I don't need AA in Bioshock or UT3 or Crysis, but Borderlands looks a thousand ways better with AA.