You're young. Stick it in a money market account or something safe for a few months until you can get some real financial advice.
Personally, if I had $5 million I would probably leave it in money market and safe CDs until this period of global deflation and low interest rates is past us. I would wait until the inevitable inflation that is coming in a few years, and when interest rates are over 10% (hopefully), put a couple million in fixed annuities that will pay out monthly for the rest of my life, put 1-2 million in safer investments, and invest the other million in risky stocks with a high potential payout.
That way, I have guaranteed income for the rest of my life from the annuities, enough to live off of, and can hopefully see some better returns from the rest of the money. A good financial advisor can give you a better strategy.
But otherwise, investing in a pure cash portfolio is super-exposed to inflationary risk, and very low-growth.
In other words, a financial trade isn't a bet on your insight. It's a bet that your insight is sharper than the person on the other side of the trade.
Recently there was some discussion about simplest possible portfolio on Dilbert blog: http://www.dilbert.com/blog/entry/worlds_simplest_portfolio/
There is a very likely chance that the first four options could all suffer losses in the immediate future, which is a needless risk.
I think staying out of the market until the current mess passes would be better rather than risk your initial investment by investing right this second.
Put 30% in VTI - the Vanguard Total Market Index (basically all US stocks).
Put 30% in EFA - the Europe, Australasia, Far East first world country index.
Put 10% in RWR - an index of U.S. real estate.
Put 10% in RWX - an index of international real estate.
Put 15% in Treasury Inflation Protected Securities.
Leave 5% highly liquid.
Minor variations on this are fine. The key is invest in broad market indices, diversified among stocks and real estate, domestic and internationally, with a bit of cash set aside for rainy days. Any other strategy involves speculation (trying to be smarter than the market), and unless you think you really know what you're doing, you shouldn't speculate.