re: Poker & Sample Size
It depends how big your win-rate is. If you're winning at 40bb/100 over 5000 hands, you're likely a winner. If you're winning at 1bb/100 over 15000 hands, its hard to tell if you're a winning player or not.
It also depends on the game. Games with lower variance (i.e. less short term luck) require fewer hands to determine if you're a winner. So Razz for example, would require fewer hands than limit hold'em to determine if you were a winner.
Just post your win-rate, # of hands, and your preflop VPIP, PFR, and aggression percentage stats. From that data alone we can usually tell if you're a solid player or not.