Buying gadgets can require sorting through options. Do you go for the faster processor or more memory?

Below is some guidance about what is worth paying for.

PAY FOR PC MEMORY, NOT SPEED When you buy a new computer, you are often given the option of upgrading the processor and adding more memory, or RAM. If it is an either/or proposition, go for the RAM. Processors are usually fast enough for most people; it is the RAM that can be the bottleneck.

Here's a side note on RAM: Do not buy it from your manufacturer; RAM purchased from online retailers is just as good and considerably cheaper.

PAY FOR COMPONENTS, NOT CABLES When a salesperson starts pushing $1,000 A/V cables on you for your media system (this price is not an exaggeration), walk away. Many connections today (H.D.M.I., optical audio) are digital, which means there is little to no signal degradation along the length of the cable. Small exceptions can be made if you are connecting components across long distances - say, more than seven meters. Even with analog connections, it is highly likely that you will not be able to hear the difference between a cheap cable and an expensive one.

PAY FOR SENSOR SIZE, NOT MEGAPIXELS Although the industry still promotes one now-useless specification and obfuscates a far more important one, just know this: Almost all cameras have enough megapixels now; it is the size of the image sensor that largely determines the quality of an image. Sensor size is confusing, because manufacturers use different formats. In response, someone created sensor-size.com, a site that converts sensor measurements for an easy comparison.

PAY FOR APPLECARE, NOT MOBILEME Apparently, Apple makes some products that people really like. But MobileMe, Apple's suite of cloud-based services, does not have the same draw. Maybe it is because most of what Mobile Me can do is available free from other companies. Web e-mail? Gmail. Photo storage? Flickr. Cloud storage? Dropbox. There used to be one killer app on MobileMe - Find My iPhone. But now that is available for free to all iPhone users, so that is one less reason to pay $99 a year for the service.

But saving on MobileMe frees up some cash for something more valuable, and that's AppleCare, Apple's extended hardware coverage and phone support.

If you buy an Apple product without AppleCare, you get 90 days of free phone support and one year of hardware coverage (note that accidents like spills, drops and other mishaps are never covered, only malfunctioning equipment).

If something goes wrong after that, you must pay for any phone support or repair work, and the prices are high - from $30 to $50. But purchase AppleCare (which costs from $29 for an Apple TV to $349 for larger MacBook Pros) and you get three years of phone support and repair coverage.

While other tech companies offer similar plans, most are to be avoided, as calling them for help often results in, "Did you try restarting your computer?"Apple's techs are helpful and persistent and, since the company makes both the operating system and the hardware, they have the added benefit of actually knowing what they are talking about.

PAY FOR TV SIZE, NOT REFRESH RATE As Matt Buchanan pointed out on Gizmodo.com, every television manufacturer has a sweet spot on price and size. Going to 140 centimeters from 127 could cost twice as much as going to 127 centimeters from 107, so 127 centimeters is where you would get the most for your money.

But one thing you do not have to spend much time looking up is a television's refresh rate, measured in hertz. That tells you how many times per second the TV refreshes the image on its display.

Many TVs now have a refresh rate of 120Hz. More expensive models can be twice as fast, but your eyes would be hard pressed to tell the difference.

The New York Times