My company's 401K offers a fixed rate fund (administered thru Vanguard), in addition to a handful of the funds that Vanguard manages. The fixed rate for 2014 is 5.1%. Would most people stick to leveraging this sure thing rate or try to diversify the money into some other funds? I also have an IRA that I keep a b it more risky and diverse, in additional to some taxable index funds.