Fire Ameriprise immediately. Do not give them any more money or allow them to reinvest dividends or capital gains in their high-load mutual funds. Once you have determined what funds you own and if any are proprietary funds sold by Ameriprise, decide which funds need to be sold and which funds (if any) should be transferred in kind to the new custodian. In your shoes, I would look at Fidelity and Vanguard. Check out the bogleheads forum for discussions of the pros and cons of both companies. I use both, but prefer Fidelity because of the service, the website, and the bricks and mortar offices.
Nothing wrong with the 500 index fund in the new 401k for now. Eventually you will develop an asset allocation and you can make changes then if needed. Just get started now!