Form what I understand you can set up a "Roth" IRA with any fund company or bank. In other words if you want to go really conservative you can make a CD from your local bank a "Roth" IRA.
You just need to talk to one of the fund advisors, so they can help you chose a fund. I like the T.Rowe Price 2030 fund (I think that's the name of it) any way the reason I liked it was because it adjust for you. I'm suppose to retail in 2030. They adjust the investment type (cash/stocks/bonds/etc) ratios for you as you get older. This was the first of it's kind when I was rolling over my 401K from work, but now all the fund companies are offer this type account.
The main thing to ask for is a "No-Load" mutual fund. These are mutual funds that don't charge any commission to purchase them. They may have a annual maintenance fee, but when you reach their minimum balance these fees are waved.
You can compare mutual funds by their "Average Annual Total Returns" they will report 1 year / 5 year and 10 year performance and their yields to see how well they performed long-term. Write down any questions you may have and don't hesitate to call a fund rep to ask question... that is what they are there for... even if you decide you don't want that fund/company. Don't be afraid to ask questions.
I currently have Vanguard and T.Rowe Price accounts. There are other good companies such as Merrill Lynch, Smith-Barny (this is current 401K from work), Eaton Vance, Legg-Mason, Fidelity... you can pick up a Money or Forbes magazine to learn about other good fund companies. Some other good sites to learn about mutual funds are Morning Star, The Motely Fools and MSN.com gives some info too on stocks & mutual funds.
Good luck... I hope this helps.