NEW YORK (FORTUNE) - Fidelity Magellan is the Coca-Cola of the mutual fund world -- the closest thing the industry has to a signature brand. So it was big news in late October when the nation's largest mutual fund empire said that Robert Stansky was resigning as Magellan's manager and would be replaced by Harry Lange, an 18-year veteran and respected stock-picker known for a more aggressive style.

The change was long overdue. Under Stansky, who became manager in June 1996, Magellan trailed the overall market for five of the past eight years. During his tenure, the fund produced an annualized return of 6.9 percent, compared with 8.1 percent for the S&P 500, according to Morningstar.

Lange, 53, is a solid replacement. The son of a junior high school math teacher, he caught the investing bug when he was just eight years old. His investments helped him pay his way through the GM Institute, where he studied engineering, and Harvard Business School.

Lange joined Fidelity as an industrial and machinery stock analyst in 1987, and became manager at Fidelity Capital Appreciation in 1996. There, he displayed occasional streaks of Peter Lynch's aggressive, gunslinging approach.

When the market plunged following the terrorist attacks on Sept. 11, 2001, Lange doubled his technology stock holdings to 30 percent of the fund's assets. As a result, the fund roared back as the market recovered. In his nearly ten years at Capital Appreciation, Lange posted an average annual return of 9.7 percent, compared with 8.4 percent for the S&P 500.

We caught up with Lange in early November to talk to him about how he got interested in investing, his plans for running Magellan and ballroom dancing. Excerpts of the interview appear below:

When did you start investing?

When I was eight years old. My father got interested somehow and we decided to go into an investment club together. I used money that I got shoveling snow and mowing grass. I bought AT&T as my first stock with $250. It had a 5 percent dividend.

I thought it was a lot easier collecting dividends and hoping the stock would go up then it was to be out there mowing grass. I think I made $30 after commissions. That was a lot of money for me.

When did you join Fidelity?

I joined in 1987 as analyst covering industrial and machinery stocks. My first day was the day of the crash. I left Wellington Management on the Friday before the crash and joined Fidelity the next Monday. I was glad I didn't take the month off.

It was a scary day to start. Everyone was just staring at screens in disbelief. IBM would trade at $104. Then it wouldn't trade for a half an hour and then trade at $87. I'd never seen a stock market like that.

Did you ever work with Peter Lynch?

We all did. He interviewed me when I came from Wellington. During the interview he was asking me for some of my favorite and least favorite stocks. He called them up and made the trades right there during the interview. I thought that was a good sign that I was going to get a job offer.

What did you learn from working with him?

He really wanted to hear the story in simplified way. What's the main factor that's driving this company? What's going to make people want this stock? He didn't want to hear, 'Well, operating margins in Europe were down 2 percent.' He just wanted the main factor that's driving the company, like, 'This auto supplier is being driven because people can't get enough tires and they're sold out through 2007.'

How did you do so well at Capital Appreciation?

One of the things is adapting to the market. I don't think the same rules that I learned from Peter Lynch still worked five years later. As hedge funds become more active and people move on news a lot quicker, it changes when you're buying and selling. I'm always trying to buy the right stocks but in terms of buying them and when I'm double weight and equal weight, that gets into investor psychology. That's something you have to develop over time.

Was running Magellan a job you were hoping to get someday?

It's like a dream to join Fidelity as an analyst and then get to manage the flagship fund. I wasn't trying to position myself for it. But it was something I always dreamed of. It turns out I was in the right spot at the right time, I guess.

How are you going to run Magellan?

Similar to how I ran Capital Appreciation. It'll probably be mostly in the growth camp, especially now with growth stocks the cheapest they've been in 30 years. I'm finding a lot of great opportunities in growth stocks.

I'm gonna make it a go-for it kind of fund. When I get high conviction I'll make the bets.

How will you handle Magellan's huge asset base?

I'm probably going to have a lot more names in the fund. I'll have to rely a lot more on the analysts here to help watch those because there will probably be a lot more companies than I can keep on top of every minute.

I can buy pretty much any public company in the world. With the multiple trillions of dollars of market cap out there it's pretty small in the pond that it's playing in.

What's your goal?

To beat the S&P 500 and my peer group. I don't want to just beat them by 1 percent. I really want to shoot the lights out here.

What do you like to do in spare time?

Ballroom dancing is main hobby. I have a professional woman partner that I compete with.

Any big competitions coming up?

One in Las Vegas in about a month but it depends on this fund. I may skip and wait until early next year.