There are precisely two ways to explain the gap between the stratospheric valuation of a Net-stock wonder and the merely rich valuation of a successful competitor: Either the upstart is hideously overvalued, or the established player is grossly undervalued.

Just for argument's sake, then, let's agree that

E-Loan

(EELN)

, the recently public online-mortgage broker that will shortly report second-quarter revenue flat or down from the previous quarter, isn't really worth $2.4 billion. The better question for the time being is whether

Intuit

(INTU) - Get Report

, E-Loan's far larger competitor, is worth

only

$5.6 billion.

Consider how Intuit's pieces might be valued if it were an Internet start-up. Its

QuickenMortgage

business alone, with $400 million in first-quarter loan originations (compare with E-Loan's $480 million) ought to be worth about the same as the entire Dublin, Calif., start-up. This is especially so because Intuit relies less heavily on mortgage refinancings, an area that has slowed dramatically as interest rates edge up. It's also because Intuit's sales are more evenly spread out geographically, leaving it less vulnerable to a slowdown in a regional economy. So now the rest of Intuit would be worth $3.2 billion.

Now factor in the potential value of Intuit's burgeoning insurance-quote referral Web site,

InsureMarket

. The newest proxy for that business is Internet start-up

InsWeb

of Redwood City, Calif., which is in the final stages of its IPO process. At the maximum proposed price of $13 a share, investment banker

Goldman Sachs

is valuing tiny InsWeb at $419 million. InsWeb's annualized revenue, based on the first quarter, is $12 million. Let's make the not-over-the-top assumption that InsWeb's IPO slightly more than doubles, giving it a valuation of a cool $1 billion.

That values the rest of Mountain View, Calif.-based Intuit, which has more than $800 million in annualized sales, at $2.2 billion.

Now for the fun part. As of April 30, Intuit had $1.8 billion in cash, short-term investments and marketable securities. Some of the latter, through ownership of stock in

Excite@Home

(ATHM) - Get Report

and

CheckFree Holdings

(CKFR)

, has since been sold. But you don't need an HP 12-C financial calculator to know the market isn't exactly awarding Net-style valuations to the rest of Intuit's business, a profitable tax-preparation and personal-finance software operation. And never mind that the mortgage, insurance and other financial-services components to Intuit's business just might provide some operating synergies to the one company that controls them.

"I would argue that the businesses go well together," deadpans Intuit fan Lise Buyer, Internet analyst with

Credit Suisse First Boston

in Palo Alto, Calif. Among the many reasons Buyer finds being an Intuit supporter profitable is that her employer rakes in hefty fees supplying investment-banking services to Intuit. Her firm, for example, handled the recent sale of a large chunk of Excite@Home stock, which Intuit had acquired as part of a strategic investment in Excite. But Buyer's got decent credibility on Intuit. In April she removed a coveted strong-buy recommendation from the stock and replaced it with a buy, her current rating.

She says she's stingy about strong buys, saving those for stocks she thinks clients should "drop everything" to go purchase. Still, "Intuit has been my single favorite call," says Buyer, even though she warns that Intuit's fiscal quarter ending this month will compare unfavorably to last year's July quarter because of the pop from a product introduction a year ago.

But the success of Net "pure plays" -- companies that are in only one business, making simpler the task of analyzing their values -- should only make Intuit's overall potential stand out in starker contrast.

"The huge success of the E-Loan offering makes it apparent that there is tremendous value there," she says.

Or, of course, the bidding up in value of a first mover as a proxy for the entire online financial-services sector simply is further proof that things have gotten way out of hand.

Adam Lashinsky's column appears Mondays, Wednesdays and Fridays. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Lashinsky writes a monthly column for Fortune called the Wired Investor, and is a frequent commentator on public radio's Marketplace program. He welcomes your feedback at

alashinsky@thestreet.com.