It depends on the game and possibly the console region: http://en.wikipedia.org/wiki/PlayStation_(console)#Regional_...

Are you talking about the Japanese version of Final Fantasy VII or the western version ? I have the Japanese version at home, I can check quickly if needed.

Both versions use O to accept and X to cancel. In the european FFVIII hovewer it was switched around. I think only early and rushed ports of japanese titles used O to accept on the playstation.

It's still true today, for instance dark souls on the ps3 uses O to accept on the japanese version and X on the western.

I'm still not sure why Sony did that by the way. While I'm willing to believe that X strongly means "bad/false" in japanese, I don't feel like it really means "accept" in western cultures as far as I know. When the playstation came out I don't think I would have had a lot of trouble accepting O for accept and X for cancel.

I think in FFVIII it was Triangle to cancel. (O was the menu button.) They completely jumbled it all up for some reason.

Triangle was the menu button, O for cancel, X to accept/action, Square to play Triple Triad.

I believe I had to remap 'menu' back to Triangle when I played through it on my Vita last month. Could be misremembering though.

It depends on the version of the console. Japanese Playstation Portable and Vita have the O button as "accept" - but I have noticed that not all games respect that. European games played on a Japanese Vita will use X for accept, but on the Playstation Portable most games will use the system settings, rather than their own(there were exceptions, however).