0 Capital-Gains/0 Div Taxes 25% tax bracket?

You will owe 15% tax on any capital gains/qualified dividends that fall into the 25% bracket and no tax on the portion that is still in the 15% bracket.

Note that the marginal tax rate you EFFECTIVELY pay for every dollar that goes into the 25% bracket is really 30%. That's because (assuming your cap-gains and qualified dividends have spilled into the 25% bracket), for each additional dollar of ordinary income (from your Roth conversion, for instance) you'll pay 15% on that dollar (assuming it's still in the 15% bracket) and 15% on the dollar of cap-gain/qual-div you pushed from the 15% bracket (where it was taxed at 0%) into the 25% bracket (where it's taxed at 15%). So

There's a fairly simple solution to your problem. Roth convert MORE than enough to put you into the 25% bracket, regardless of how the rest of the year pans out. Then, before you file your return, recharacterize EXACTLY as much as it takes to get you back into the 15% bracket. That way you get every possible dollar converted at the 15% rate, and none at the effectively-30% rate.

If you want to get fancy, do two such conversions, of uncorrelated asset classes (eg. stocks & bonds), into separate Roth accounts (and separate from your "main" Roth too). File a "request for extension" in April 2011 (paying as much as you THINK you'll owe). In October 2011, recharacterize whatever it takes to get you back into the 15% bracket. Recharacterize the poorer performing of the two uncorrelated conversions. But I'm getting into a whole new topic - that of "gaming" the Roth IRA conversion process - which you're probably not interested in (unless you're as big a geek as me).