Mildy obsessive compulsive types with addictive tendencies like me have to be careful at this game. Truth be told, I only started playing online for real money about less than 6 months ago, and overall I'm definitely down (like about a rent payment). So...some advice for other noobs:
To hone your chops at playing for real money, start out playing s&g tourney, not ring. That way you're getting in a whole lot of hands in without risking a whole whack of dough. Personally, I like the multi-table $1+.20 and $5+.50 games on PS. The upside is good, and you just have to place 7th or better to at least make back your entry fee (and your entry is all that's at risk). If you avoid joining the all-in fests, which are fairly common early in the game, and play reasonably tight with real hands, then you have a pretty good shot at making final table.
For me, the benefits have been tremendous. My game has vastly improved, I think because I'm no longer playing with "real" money, just tourney chips, which makes me a more aggressive, tight player. Now I'll bluff or semi-bluff in situations where I wouldn't before in ring, even though I probably should have. I also raise more often pre-flop, bet more aggressively to close the door on a winning hand after the flop, and -- yes -- even chase hands when the odds scream for it. In other words, I no longer play like a wimp, and I'm winning as a result. I've been playing on winnings for weeks now, and that feels really good.
If you win more than you lose, consistently over the long term, then you are a successful poker player, and playing s&g tourney seems to be getting me there. I've stopped the bleeding I was initially experiencing in ring, plus I'm having way more fun. This is a game, after all...