Quote from easyrider:
Being the cynic that I am I would suspect that demo gambling accounts have the odds tipped in favor of the player.
While this is clearly the case with some online casinos, this appears not to be the case at those that are reputable. That said, I have not run any statistical analysis on this, but I believe some others over at Casinomeister have.
Yahoo is using their own engine and only offers "play" money, so they very well could make the game more advantageous to you for entertainment purposes.
In any case, I would gladly sign up at any reputable online casino that was known to have fair games. Most of those use licensed software suites such as Microgaming, Wagerlogic, Playtech, etc.
The reason for this is that the player is given a huge advantage through online gaming due to internet casinos generous promotions. I'll give you one basic example. You may know of the online poker site, PartyPoker. They are affiliated with IGlobalMedia, who is therein tied to the Starluck Casino. If you have ever played at PartyPoker, sometimes when you exit the site, you are offered a link to Starluck. So new players to Starluck are offered a great deal. Make a deposit of $100 and get $100 in "bonus" money. You can cash out this "bonus" money after you comply with the casino's terms, which, in this case, you'd need to wager $1600. You might be thinking that sounds like a lot. But wait, why not just play the lowest house advantage version of blackjack with $1 bets. Blackjack has one of the smallest house advantages of all casino games and the variance is much lower than other games such as full pay Jacks or Better Video Poker, etc. So, let's assume that the version of blackjack you play has a 0.5% house advantage. Given optimal play, over $1600 of wagering, you are expected to lose $8.
This means you would be left with $92 in expected value. You can run the numbers yourself if you like, but this is a clear edge. You go into the casino with a guaranteed and known positive expectation.
THIS is how you beat the world of online gambling, not some trader's "system" to beat the dealer.