With rates where they are, all you would need is a 6% pre-tax return (not taking into account the interest tax deduction) to make the decision to invest the funds.
The Obama Administration had proposed that government pre-fill your tax return with information it collects from employers, financial institutions, etc.
If an agreement is not reached and we return to the pre-Bush tax system, the top tax rate will jump to 39.6% from 35%, dividends will be taxed at ordinary rates and taxes on long-term capital gains will increase from 15% to 20%.