how do you define 'exceptable' performance in games

[smithy1983]

there is something that realy does confuse me sometimes on this and on another forums is when people say stuff like 'fear works great with a p4 2.5 512 blah blah blah'

so what do you consider to be exceptable game performance? in frames per second wise iwith you current set ups? and what level of gfx detail do you use?