Shortly after our marriage, I committed a cardinal sin: I bounced a check.

My bride was mortified, and rightly so, because she worked for a bank in those days, and spent a fair amount of time showing little old ladies how to balance their checkbooks and avoid the very embarrassment that I had caused.

The result: She assumed control of the family finances, and for the past 30 years I've been allowed access to the checkbook only under strict supervision. Which has worked out just fine.

While this beautiful and capable woman spends Sunday afternoons negotiating the invoices and bank statements, I get to watch football, interrupted only by an occasional outburst of salty language when her numbers don't add up. Our bills get paid on time and our bank account is in the black. In short, I'm a lucky guy.

The only downside to this arrangement is occasional embarrassment when someone asks what software I use to manage my finances. As the tech guru, I'm supposed to know all about that stuff. So I've always replied that my checkbook balancer is system-independent, user-friendly and doesn't want to be replaced by a computer.

But times change, and so does technology. Several months ago, I checked the Bank of America Web site and noticed that online banking - including bill-paying - was now free for new enrollees, instead of an additional $10 a month. The system also seemed easy to navigate.

But the biggest surprise? After years of rejecting my occasional suggestion that something more advanced than a $5 calculator might make her job easier, my wife decided it was time to give technology a try. So, we joined 24 million other Americans who are banking online.

According to Jupiter Research, that's twice the number of customers who were banking online two years ago. The firm projects that more than 40 million will be online by the end of 2005.

There are several reasons for the increase, according to researchers and analysts. First, there's a change in consumer behavior - more people are comfortable conducting business over the Internet. Also, for many of us, carrying a checkbook is no longer a day-to-day necessity. We use ATMs for cash, credit cards for larger purchases, and checks to pay bills at the end of the month.

Second, banks are starting to improve their Web sites, promote online services and eliminate fees for using them. This is in their interest, because online transactions cost less to process. Collectively, banks expect to save hundreds of millions by eliminating as many paper transactions as possible.

They've also found that satisfied online checking customers tend to stick with their banks longer than the average account holder. Our experience certainly has been a good one so far.

Just realize that to set up online banking, you'll have to do some work up front.

First, consider that there are two ways to use online banking to pay your bills. Once is to authorize a direct electronic transfer to a payee who accepts them. Most credit card companies, national retailers and utilities accept online payments. Bank of America (BOA) says these payments will be made within two days, which is less advance time than you'd normally need with a paper check.

For payees who don't accept electronic transfers, such as local merchants, doctors, dentists and the guy who mows the lawn, the bank will issue a check on your behalf and mail it. Generally, you'll have to provide the bank with the number of the account you have with a merchant to identify your payment. Otherwise, the check will arrive with your name and address but no other information.

BOA says checks will generally be delivered within five days, which is about how long my wife allowed for our paper checks to arrive in the mail. The difference is that BOA deducts the payment from our account the moment it's authorized; with a paper check, the money stays in our account until the payee deposits it.

That's a hidden cost of online banking - the bank gets a better float from your money. For people with a lot of dough at one end of the spectrum, or less-fortunate folks who are constantly skirting overdrafts on the other, this might be a big deal. But because we don't fit into either category, giving up the float is well worth the convenience.

The hardest part of the job (and not very hard at that) was setting up our payees. For those who accept online transactions, it was a matter of picking their names from a list on BOA's Web site and adding our account number. To set up non-electronic payees, we had to type in their names and addresses, too. My wife did the job over several weeks as our bills fell due.

It's also easy to set up automatic payments for recurring expenses such as mortgage or car payments.

That done, paying bills is a snap. BOA displays a Web page with a single form that lists all of our established payees. Next to each name, my wife enters the amount of the payment and the date it's to be paid - a nice feature if we're going on vacation and want to have our bills paid automatically when they're due. When she's through, a single click authorizes everything. No checks to write, no stamps, no rush to the mailbox.

Likewise, BOA's well-organized Web site lets us review our payments, transfer money between accounts, and view or download a continuously updated statement that shows all our activity - electronic payments, paper checks, deposits and ATM withdrawals. If we write a paper check, only the number is recorded electronically, but we can call up a scanned image of the canceled check to see who it was made out to.

BOA's online system can also interface with Intuit's Quicken and Microsoft Money for those who handle their finances with these programs.

My wife says she's eliminated 90 percent of the paper checks she used to write. Balancing the checkbook is much easier, and she can call up a running statement whenever there's a question. She has only one gripe - she would like a memo field on the checks the bank writes to non-electronic payees, so she can explain the payment - for example, a charitable donation or a single check that covers multiple insurance policies.

For many potential customers, the biggest question marks in online banking are reliability and security. BOA and most others offer to reimburse customers for late charges if the bank fails to make a payment on its scheduled date. They also say customers won't be liable for fraudulent use of their accounts.

Eventually, this gets down to a matter of trust. There have been reports of breaches in online banking security. Most involve leaks of e-mail addresses and other information, as opposed to embezzlement or fraudulent access. But nobody knows for sure because banks are notoriously unwilling to report these incidents (or old-fashioned scams, for that matter).

I figure I take a far greater risk every time I give a credit card to a waiter who disappears into the back of a restaurant.

For the time being, at least, online banking is a hands-down winner.