effect of 401k

According to the Social Security Administration, No.

SSA counts only the wages you earn from a job, or your net profit if you're self-employed. Non-work income such as pensions, annuities, investment income, interest, capital gains and other government benefits are not counted and will not affect your Social Security benefits.

HOWEVER, depending on your income levels and the type of 401k or IRA you have, the withdrawls could impact your taxes. You will also want to be VERY careful that your withdrawals are within the distribution guidelines for your plan in order to avoid penalties.

FURTHERMORE, before you make any withdrawals, I would urge you to make sure that you have a comprehensive retirement plan that -- most importantly -- guarantees you adequate lifetime income for the rest of your life, as well as covers your insurance needs.

If you have not already, you may want to consult with a financial planner. Most people only retire once. It is a very BIG deal and having an expert to help you create an overall plan for your money can be incredibly helpful.

If you would like NewRetirement to match you to a prescreened retirement planner, continue here:
https://www.newretirement.com/Services/Professional_Financial_Advisors_Advice.aspx

Also, you mention that you have a 401k. Most financial experts do recommend that you rollover your 401k to an IRA when you retire. Learn more about rollovers here:
http://www.newretirement.com/Services/Rollover.aspx