Excerpt: Conventional retirement wisdom tells us that when you leave a job, you should roll over your 401(k) to an IRA. Rollovers allow you to continue delaying taxes on your nest egg as it accumulates and avoid an early-withdrawal penalty. But if you have an especially good 401(k) with your old company, it may be better to leave your retirement money there or roll it over into your new company's 401(k).  MORE >>