(FORTUNE Magazine) – Sometimes nice guys do finish first. Clay M. Biddinger was only 26 when he left his job as sales manager for a computer and production equipment leasing company in Southfield, Michigan, back in 1981 to make it on his own. Smart, friendly, and modest, Biddinger had a natural interest in figuring out what other people need, and that quality had won him several loyal customers. One, the controller of a local bus company named Indian Trails, was so impressed with the young man that he handed him $100,000 of the company's money to invest in his business. Says Biddinger: ''He told me, 'I want to be part of you when you're getting started.' '' Biddinger couldn't put the cash to work right away, but his two partners also had a small industrial lighting company, and one day they asked if he could lend money to their business to see it through a cash-flow crunch. ''I was young and naive, and I got sucked in,'' he says. The venture failed; he and the partners broke up. ''The people at the bus company didn't write a contract; there was no paperwork. I could have called and said, 'Sorry, I lost your money.' '' But that wasn't Biddinger's character. ''I was embarrassed and mad. I worked probably 20 hours a day finding customers, until the pressure got too great. Then I'd take a couple of days off and run to blow off steam, to let myself know everything was okay.'' By the time his first fiscal year ended eight months later, Biddinger knew he could repay the money with the promised 16.5% interest. Virtue is its own reward. In his frenzy to salvage his honor, Biddinger also got his business off the ground. ''When I came up for air, I'd even eked out a $16,000 profit. I had ten leasing accounts, including GM. I said, 'Hey, I can do this. I'm rolling.' '' Biddinger's Sun Financial Group hasn't stopped rolling since. It leases everything from computers to satellite dishes to some 600 customers, including GM, ITT, and Automatic Data Processing. For the past fiscal year, Sun owned and managed more than $350 million of assets, up 35% from 1992, bringing in revenues of better than $25 million. Headquartered in Tampa, it has offices in Jacksonville, Fort Lauderdale, and Orlando, Florida; Rutherford, New Jersey; Minneapolis; and Ann Arbor, Michigan. HOW DOES SUN COMPETE with giants like GE Capital, U.S. Leasing, and AT&T Capital? Reflecting the founder's character, it aims to be nice to customers. ''It's a high-touch, high-understanding business,'' says Biddinger. ''You build relationships where you can communicate. You say, 'Here's the problem we've seen elsewhere. Do you have a similar one we can assist you with? If we can't solve it, we'll find someone who will.' '' And Sun follows up on the gritty detail work that entrepreneurs do better than big companies, such as testing and reconditioning used equipment and finding buyers for it. For example, it recently leased a $60 million teller terminal network for more than 600 Barnett Banks branches in Florida. Sun initially guessed that the 6,000 computers, terminals, and other items it replaced would be worth about $250,000. But then Sun found buyers in Czechoslovakia and Russia who were eager for the technology. Barnett will get more than $1 million for the equipment. You can't treat your customers well if you don't treat your employees well. This year Sun is matching 100% of contributions to the 401(k) plan, up from 50% last year. Other benefits include a stock appreciation plan for key people (Biddinger has set aside 21% of Sun's stock for it) and free college tuition for employees who want to improve their career prospects. His salesmen get to be entrepreneurs themselves. ''They create their own business with their customers, and Sun is like a support system behind it. It's like a free franchise.'' Most were senior sales managers in larger companies before joining: ''You're calling on people like chief information officers or chief financial officers, and you're not just trying to sell a widget. You've got to know all the bases, you've got to have some horsepower between the ears.'' There's no cap on the commissions they can earn. ''I hope everyone makes five times more than I do. Guess what the performance of the company would be in that situation.'' Being nice means listening to things you may not like to hear. Biddinger spends 20% of his time accompanying salesmen on calls so he can hear what the customers think Sun is doing right -- and wrong. ''You can't be sitting behind a desk in a big office pulling the strings,'' he says. ''Sure, you still have to make the decisions -- but the customer tells you what strings to pull.''