If you’ve been wondering whether to invest by computer, the answer is, “Absolutely yes.” The time has come, even for technodummies like me who try new things later rather than sooner.

Financial transactions are cheaper on the Internet for investors who buy products that carry sales commissions. Trading is sufficiently secure and the systems are generally pretty simple.

Some brokers maintain their own proprietary networks that you access with special software. But increasingly, they are choosing to open “offices” on the Internet. To reach a virtual broker, all you need is a modem, which links your computer to a telephone line and a Web connection.

Once you’re on the Web, you can browse from firm to firm, checking the prices and services.

Mutual fund investors will find it especially easy to assemble a portfolio online.

Some 50 discount brokerage firms maintain mutual fund supermarkets, where you can buy and sell hundreds of no-load (no sales charge) mutual funds at zero cost. Several of these supermarkets now accept orders over the Web. Among the leaders:

– Jack White, with more than 1,100 no-fee funds, at www.jackwhiteco.com (800-753-1700).

– Charles Schwab, with some 800 no-fee funds, at www.eschwab.com (800-435-4000). Schwab is especially strong on investor services.

– Accutrade, with some 700 no-fee funds, at www.accutrade.com (800-494-8939).

Before opening an account, check for other fees, such as annual maintenance fees or fees for selling a fund within a short period of time. With some no-load funds, you have to pay a $25 to $45 commission.

Online discount brokerage firms also sell load funds, stocks, bonds and other securities. But for buying stocks, the firms listed above are not as competitive as some others.

If you want to buy stocks at a rock-bottom transaction cost, check:

– Datek (www.datek.com, 212-514-7531; minimum commission, $9.99).

– Waterhouse (www.waterhouse.com, 800-555-3875, $5,000 minimum transaction, minimum commission $12).

– E*Trade (www.etrade.com, 800-786-2575, $14.95 minimum commission).

– Discover Brokerage (formerly Lombard, still at www.lombard.com, 800-566-2273, $2,000 minimum transaction, minimum commission $14.95).

Each of these online brokers has its little quirks. For example, they might charge extra for letting you talk to a human broker or for providing current stock market quotes (quotes usually come with a 15- or 20-minute time lag).

You also might not be allowed to sell a stock short that is, bet that the stock price will fall.

As time passes, you’ll see online discount firms offering more services such as easy links to free stock research, automatic price updates on the stocks you follow, calculators for figuring your portfolio’s percentage return, and the right to write electronic checks on your online account.

Before opening an account, find out how you can place an order if your computer crashes. Some firms tie you in by touch-tone phone, but you’ll want to be able to reach a human broker, too.

For privacy, your e-mail statements will go over an encrypted line. For security, Waterhouse and Discover don’t let you make an online cash withdrawal, but Datek and E*Trade do.

Your account is insured by the Securities Investor Protection Corporation for up to $500,000, just as traditional accounts are. Online firms typically carry additional private insurance.

Needless to say, you shouldn’t embark on this adventure until you’ve mastered your computer, says John Bajkowski, editor of Computerized Investing, a newsletter from the American Association of Individual Investors in Chicago.

A few full-service brokers are gingerly testing the Web. They’re worried about bypassing their commissioned sales force, so they’re merely advertising their services and providing some limited ways for investors to do stock research.

But for the hot-wired generation, that isn’t going to be enough. Merrill Lynch has announced that it will eventually let its customers trade online, although we don’t know what the commissions are going to be.

Something else we don’t know is how fast online brokers will be able to respond to a crush of sell orders.

In the Crash of 1987, some no-load fund investors weren’t able to sell because the telephone lines were jammed. That was fortunate, as things turned out, because the market didn’t drop much further and soon came back.

Maybe a traffic jam on the Web would turn out to be a good thing, too.

A few years from now, a financial firm that’s not on the Web will effectively not be in business.

Managing money is the third most popular use of PCs (after games and teaching aids for children), according to a study by Jupiter Communications and FIND/SVP, New York City research firms on emerging technologies.

Nearly 7 million households are using assorted investment-related services, Jupiter says. Nearly 3 million are checking stock quotes.

Forrester Research, a Cambridge, Mass., consulting firm, estimates that the number of people with online trading accounts will approach 1.2 million by the end of the year and reach 10 million in 2001.

Investing by Web is not only convenient, it’s cheaper for investors who buy stocks and other products that carry sales commissions.

With the click of a mouse, you can compare the fees charged by one online broker with another. As a result, fees and commissions are coming down.

There are far too many interesting Web sites to list in a single column. But here are some places for mutual fund investors to start:

– NETworth (http://networth.galt.com) a great free site, containing pots of fund information and historical data. You can get the funds’ current performance as tracked by Morningstar. There’s also a spot for stock investors to get quotes and company information.

– The Mutual Funds Home Page (http://www.brill.com) also jammed with mutual fund stuff. You’ll find manager interviews, fund Web sites and 800 numbers, and links to other financial sites.

– The American Association of Individual Investors (http://www.aaii.org) for an unending course in personal finance and investing, including computerized investing. This summer the site is free.

– I suppose I should blush for mentioning something as old-fashioned as a book, but try The Savvy Investor’s Internet Resource, by Bryan Pfaffenberger and Claire Mencke (IDG Books, $34.99). It takes you through every type of investing and shows you how the Web can help.

For both newbies and regular investors, this book is the best site of all.

Syndicated columnist Jane Bryant Quinn can be reached in care of the Washington Post Writers Group, 1150 15th St., Washington D.C. 20071-9200.