Not prepared? You can still retire, but you might have to work part time, scrimp a little, tweak your investment strategy -- and maybe hold a garage sale.

As the baby-boomer generation reaches retirement age, many are facing the harsh reality of a less-than-cushy nest egg. Some put their kids through college at the expense of long-term savings. Others simply didn't save enough.

Indeed, the 78 million Americans born between 1946 and 1964 are on track to replace about 60% of their annual incomes after retirement, according to the Fidelity Retirement Index. The national survey by Boston mutual fund giant Fidelity Investments also found that boomers set aside an average 4% of annual income. So much for maintaining their current standards of living.

Despite the size of their bank accounts, however, many boomers (the oldest of whom are turning 60 this year) are unwilling to put retirement plans on hold. With less money to live on and life expectancies on the rise, seniors who failed to feather their nest eggs may have to get creative to make ends meet, says Brent Meiser, a certified financial planner.

Go to plan B

"I think a lot of people are just drifting into retirement and haven't necessarily done things like calculate

A Roth seems like the obvious choice over a traditional IRA since it has tax-free withdrawals. Not always, says Walter Updegrave.

Question: If you contribute to a traditional IRA, after many years most of your account value will be in the form of investment earnings, which are taxable when you withdraw them. With a Roth, on the other hand, your balance will be tax-free. So it seems to me that the advantage of tax-free withdrawals from the Roth in the future greatly outweighs any tax-deduction benefit you get from a traditional IRA. Doesn't that make the Roth a better deal? - Daniel Siroky

Answer: A lot of people aren't quite sure how to assess the value of contributing to a traditional IRA vs. doing a Roth. That's not surprising, given the number of factors that can affect which is the better choice for a given person in a given circumstance.

Generally, I think having at least some money in a Roth IRA (or Roth 401(k), if that option is available to you) is good idea for several reasons. But before I get to them, I'd like to step back and explain how both traditional and Roth IRAs work in a way that, I hope, will give you and others a better understanding of them and help you decide which type to fund. More from Money on CNNMoney.com:

I'll start by stating a premise that many people overlook or simply don't understand about traditional and Roth IRAs - namely, that theoretically at least, they're equal in terms of the tax advantages they offer