Look at the facts.

For further reading:
Charles Ellis’ “Winning the Loser’s Game” – check it out on Amazon
“Debunking Some Myths and Misconceptions About Indexing From Vanguard
“401(k) giant Fidelity sued over its own plan” From The Wall Street Journal’s MarketWatch
“Fund Investors Lag as S&P 500 Nears All-Time High” from Forbes
“Dalbar’s Harvey: Individual Investors Brilliant at Mistiming Markets” from MoneyNews
“401(k) Savers are Confused and Stressed” from The Wall Street Journal’s MarketWatch
“8 Retirement Planning Mistakes to Avoid” from Yahoo Finance
"A Yale Professor Takes on the 401(k) Industry" from The Huffington Post
"Upside-Down Bash on Index Investing" from The Huffington Post
"America Can’t Afford Wall Street’s Terrible Investment Advice" from Time Business
"The castaways of your 401(k): index funds" from CNN Money
"The conspiracy for failure in 401(k) plans" from The Houston Chronicle Online
“Luck Versus Skill in Mutual Fund Performance” From the Fama/French Forum
“Almost No One Can Beat the Market” From The Wall Street Journal’s MarketWatch
Daniel Solin’s “The Smartest Portfolio Book You’ll Ever Own” - check it out on Amazon
Shlomo Benartzi's "Save More Tomorrow" - check it out on Amazon

Additional Resources:
Four Biggest 401(k) Conflicts
Where do you fall on the plan design continuum?
What happens when expenses are tied to assets?
What do high expenses really do to participants’ savings?