Personally I hate that lack of information in videogame profiles. We know almost every actual release is compatible, but when it comes to much older games...
Widescreen resolutions did not become prevalent until 2007, although there were some exceptions prior to that, they are uncommon. You can pretty much assume most "good old games" do not support widescreen resolutions out of the box. You can however consult wide screen gaming forum as somebody else mentioned for info on how to tweak many older games to display widescreen with varying degrees of quality, stretching, etc.
I think pretty much anything from 2007 forward is going to support widescreen with the exception of some indies perhaps.