malakito: My 401k administrator says that we have to take all of our money with us when we leave and roll it over into another qualified plan on our own. They want to keep it simple for themselves.
If you have more than $5000 in your 401(k), your employer cannot make you take the money out or roll it over into another plan. You can keep it there if you want.
As far as the age 55 rule, I believe there is no penalty for distributions made to an employee after leaving employment if the employee turns 55 that year. However, the employer doesn't have to allow you to spread out the withdrawls and might make you take the amount you want to withdraw all at once. This can lead to a big tax bill.
One option to look at is rolling over into an IRA and then taking early withdrawls under the "substantially equal periodic payments rule" where you take out an equal amount each year for at least 5 years.
Check with a good tax advisor before making a decision.