With hundreds of models from which to choose, picking the right digital music player can be a tough task. You can ease the stress and single out the best player for you or a loved one by looking at three areas: how the player will be used, file formats and extra features.

1. Use. If you need a player for your morning jog, check flash-based machines, but if your player won't be jostled much, stick with a hard drive. Here's why:

Flash-based music players have no moving parts. That means you can attach it to your body and move vigorously with no effect. These players are very popular with people who have active lifestyles. They are tiny and lightweight and usually have excellent battery life. But they hold fewer songs than players with hard drives.

For $199, the 2-gigabyte Apple iPod Nano (www.apple .com) holds about 500 songs, according to Apple. For $50 more, you can double the capacity. Other well-reviewed players include the Cowon iAudio U2 (www.cowonamerica .com) ranging in price from $99 to $269 and in capacity from 256 megabytes to 2GB; the Dell DJ Ditty (www.dell.com; $99, 512MB); and the Samsung YP-T7X (www.samsung.com; $150, 512MB).

Hard drive players are heavier, but they hold much more music. They also tend to have larger screens, more bells and whistles (like the ability to display digital pictures) and better interfaces. A good interface is crucial for any player with thousands of songs. You'll want to be able to locate a song or artist quickly and easily.

Apple's iPod has gained a huge following because of its easy-to-use interface. Its 30GB model retails for $299; add $100 for twice the capacity. The iRiver H10 (www.iriveramerica.com; $300, 20GB) and Archos Gmini XS 200 (www.archos.com; $230, 20GB) are other alternatives.

The beauty of hard drive players is you pay less per megabyte of storage. But this might lead you to buy a player with more storage than you need. For example, a 60GB player can hold as many as 15,000 songs. That's probably overkill for most people. However, unused space could be used to store data files, such as picture files.

2. File formats. There are two ways to get music from your computer to your player. You can copy music from CDs that you own (a process known as ripping), or, you can purchase and download music from online stores. This is where it gets tricky.

The iTunes Music Store (www.apple.com/itunes) uses an encrypted version of AAC (Advanced Audio Coding). Only the iPod accepts and plays copy-protected AAC files. So if you've already purchased music from iTunes, buy an iPod.

But most music sites use encrypted WMA. The iPod won't play such files, but most other players will.

3. Extra features. If you have a few models in mind, look at the extras. This can make or break a player. Is radio an important feature? Some players include FM radio. Are you particularly fussy about the sound? Look for a customizable equalization feature.

Do you want to show off your latest vacation pictures? Many models can do that. And, of course, video is the latest and greatest feature. But remember to get the music right first. After all, that is its primary function.