As a tax professional, your goal should be that when you file your tax return you and the government should be even (i.e., you don't owe them and they don't owe you). If the government owes you, you've given them an interest free loan. IMO, you should not use the government as a savings account.
When you say that you have 25% of your paycheck withheld, is that all federal income tax withholding? or are you also considering the withholding that goes towards Social Security and Medicare (because those items don't go to paying your income taxes.)
I don't have enough information from your post, but it seems like you and your hubby need to sit down (or hire a tax accountant) and prepare an estimate of what your taxable income and liability is going to be for 2013. Once you know what the estimated liability is going to be for the full year, you can determine how much you and your husband need to have withheld from your paychecks each month and what you should put on your Form W-4 to ensure that your company withholds the right amount. I can tell you that sometimes even electing "single" status isn't enough to get to the right withholding amount - you may have to ask your company to withhold an additional $ amount from each paycheck (which you can also designate on the W-4.)