The last time I checked into United Online (NASDAQ:UNTD) was early February, after it reported strong second-quarter earnings. Since then, the dialup Internet Service Provider has nearly doubled in value, far outpacing the stock performance of rivals AOL (NYSE:AOL), MSN (NASDAQ:MSFT), and EarthLink (NASDAQ:ELNK).

As I mentioned then, United's big advantage over competitors is price. It charges about $10 per month for dialup access for its NetZero, Juno, and BlueLight Internet services. By comparison, AOL's charge is pushing $24 per month. At a time when AOL is losing subscribers (if it's even possible to tell how many it really has), United said today that its paying users increased 49% over the past year.

The company also reported earnings of $0.32 per share during its fiscal fourth quarter compared to a $0.07 loss a year ago. Free cash flow continues to improve dramatically, jumping 53% to $18.3 million. For the entire year, it generated $59.1 million in FCF.

That means the stock is trading at 23 times trailing free cash flow, and my back-of-the-envelope calculation/guesstimate tags it at about 18 times fiscal 2004 FCF. Not bad when you consider the 49% subscriber and 66% revenue growth.

The challenge for this company is maintaining strong subscriber growth at a time when the lure of cheaper broadband is siphoning away dialup users. But again, we turn back to its competitive advantage of lower price. There will be a market for dialup access for years to come, and with United's ISPs priced at less than half the others, its competitors have a lot more to worry about than it does.