Image: Watching television © Digital Vision Ltd., SuperStock

One of the more tiresome habits we personal-finance writers have is lecturing people about the difference between wants and needs. The things we truly need are few: food, shelter, clothing, companionship. Our wants, by contrast, are endless.

That knowledge is supposed to help you winnow out the unnecessary when it's time to cut the budget. But humans are also creatures of habit, and sometimes we grow dependent on stuff that has simply outlived its purpose. Better, more convenient, less expensive technologies may exist, but we can't discover them if we're still clinging to the old.

The following are technologies that wormed their way into our lives and that now may deserve the boot:

1. Television

For decades, TVs were up there with cars and clothes washers as items most Americans agreed were necessities of modern life. Though we still feel that way about our wheels and our washers, we've lost that lovin' feeling for our TV sets, according to Pew Research's latest "luxury versus necessity" poll. Just 42% of respondents counted TV as necessary, down 10 percentage points from 2009 and down 21 points from 2006. Among those ages 18 to 29, just 29% said a TV was required equipment.

Of course, that doesn't keep the average household from having more TVs than people: 2.86 sets, according to a Nielsen report, versus 2.59 people, according to the Census Bureau. And 10% of those polled insisted a flat-screen TV was necessary to their lives.

But most of us are cluing in that we needn't be tied to a box, however slim and gorgeous, in the living room. We can watch our favorite shows online and on our smartphones. We still like our TVs, sure, but we no longer love them. Now it's our computers we say can't live without; 49% of the general public and 53% of those 18 to 29 say their home computers are a necessity.

2. Telephone land line

A decade ago, nearly everybody had a land-line phone. Now, one in four households does without land-line service. The younger you are, the less likely you are to see a land line as essential: While 77% of those 65 and over saw it as necessary in the 2010 Pew Research poll, only 46% of those 18 to 29 shared the same view. Not surprisingly, 59% of younger people see a cellphone as a necessity, compared with just 29% of those 65 and over.

Liz Weston

Liz Weston

One big issue keeping some people tied to their land lines is 911 service. Emergency services typically can pinpoint your location when you call from a land line, even if you can't "state the nature of your emergency." Such enhanced 911 capability isn't universal with cellphones yet, although the typical new phone is GPS-enabled and the Federal Communications Commission is requiring wireless carriers to upgrade their services to transmit more precise location information to public-safety agencies.

3. DVD player

Blu-ray won the format wars against HD-DVD, but the victory was Pyrrhic, since physical media of all kinds -- DVDs, CDs, video games on disc -- are rapidly giving way to Internet streaming and downloads. It won't be long before those shiny flat circles join LaserDiscs, VHS and Betamax on the scrapheap of movie technology.

Exactly how we'll get our movies is the subject of great commercial battles at the moment. Netflix has the early lead, but such services are now attracting the attention of some of the biggest names in consumer tech. Amazon Video is building its audience by offering streaming to its Amazon Prime subscribers, and Apple TV is gearing up to be a major player in this market. Facebook and Google's YouTube, among others, are also rolling out services. All can be accessed from your computer, or you can plug an add-on unit such as Roku or Boxee to your TV set.

4. Physical music collection and dedicated player

Just for grins, ask your grandpa how proud he was to upgrade to an eight-track back in the day. The sound quality quickly deteriorated and the tapes tended to jam, but they were portable -- you could play them in your home and in your car!

Now, of course, you can carry thousands of songs in your pocket, and the days of the single-purpose MP3 player are numbered. Smartphones have pushed aside iPods as the music players of choice, just as digital music collections have shouldered aside CDs. Gone are the days when you had to spend an afternoon organizing your disks; now you can do it with a click, and cloud storage means you can access your tunes from anywhere.

Audiophiles may cling to their vinyl, but the rest of us should be more than ready to chuck physical media.

5. Cable or satellite TV

Most Americans don't see their paid televisions subscriptions as a "need," exactly, but it took the recession to get many to cut the cord.

Cable companies lost more than 2 million subscribers in 2010, according to research firm SNL Kagan. Some switched to satellite, but industry watchers say fewer new households -- mostly young people starting out -- are signing up for either cable or satellite.

And when you think about it, why should you pay for a bunch of channels you don't watch when you can get most of the ones you want online?

6. Desktop computer

Kiss your tower goodbye, because laptops, tablets and smartphones are making it obsolete. Given how most people use their devices, any advantage a desktop may offer in speed and performance is probably overkill.

Besides, it's all about mobility. Wireless hotspots mean you no longer have to be tied to your desk in order to work or play. Industry experts predict desktops will become harder to find, much as flat screens have muscled out analog TV sets.

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That's not to say you should toss your current desktop in the trash. But when it inevitably dies or becomes so slow you want to kill it, a laptop or tablet will be the logical replacement. If you can't live without the big-screen home computing experience, you can buy a monitor and even a mouse to use with your portable device.

7. Email

Email isn't going away, but often there are better ways to communicate. Texts and instant messages are more appropriate for short and urgent messages, particularly if you're trying to reach someone under 30. She may not have a smartphone to check her email, but she's almost certainly texting. Social-media sites are often a more suitable way to keep up with family and friends. Complex or sensitive topics should be discussed on the phone or, better yet, face to face.

And if you're having a major dispute with a business or government agency, old-school letters are the way to go. In some cases, such as a billing or credit dispute, committing the problem to paper is the only way to ensure your federal rights are preserved.

Liz Weston is the Web's most-read personal-finance writer. She is the author of several books, most recently "The 10 Commandments of Money: Survive and Thrive in the New Economy" (find it on Bing). Weston's award-winning columns appear every Monday and Thursday, exclusively on MSN Money. Join the conversation and send in your financial questions on Liz Weston's Facebook fan page.