@edgarblythe,
Mine were all in Vanguard Funds - they are the low cost provider and lots of companies use them. All company 401K plans involve a small set of preselected options for those who don't want to think about it, but all also allow you to transfer funds to any of the hundreds of open funds operated by the fund manager (i.e. Vanguard, Fidelity, Merril Lynch, etc.). I simply tried to balance my contributions over funds involving bonds, income stocks, growth stocks, a few real estate funds and some international indices. I always contributed the max allowed (including the "catch up" allowance allowed for folks over 50) and even some post tax money if the program allowed that (some don't).