Every month, manufacturers unleash even more MP3 players to an increasingly confused public. Not only do these devices have wildly divergent features, but ongoing format wars mean the MP3 player you choose dictates where you can buy your digital music. These devices are anything but one-size-fits-all.

First, there's the question of design. A player can have every feature in the world, but if the design doesn't match your lifestyle or if the interface is impenetrable, you still won't enjoy it. You'll want to look closely at performance; sound quality and battery life can make or break a player, especially if you travel a lot or have the so-called golden ears of an audiophile.

Before you start checking out specific models, you should have a basic understanding of the types of MP3 players available. Note: All types of player mentioned below can play other formats besides MP3, such as WMA, ATRAC3, OGG, or AAC, but we still refer to them as MP3 players.

Hard drive-based players

Most likely, a high-capacity player can accommodate every song you've ever purchased. Hard drives run from 10GB on up, and large players such as the Creative Nomad Jukebox Zen Xtra can hold around 17,000 songs, assuming an average file size of 3.5MB per tune.

Pros: They store all your music on one device. They also tend to have more features and larger screens and are overall easier to use.

Cons: These players are usually built around a 1.8-inch hard drive; thus, they are larger and heavier than the others. Also, hard drives have moving parts, so these players aren't ideal for strenuous physical activity. Finally, most use rechargeable batteries (usually lasting 8 to 20 hours per charge) that you can't replace yourself, so after several years, you might have to pay for a new model or pay to get the battery replaced.

Micro hard drive-based players

Straddling the line between full-size hard drive-based MP3 players and compact, flash-based players, these models aim to give you the best of both worlds by using miniature hard drives (about 1 inch in diameter) with capacities of up to 6GB. Players such as the Rio Carbon can't store as much music as a 20GB Creative Zen Touch, but they feel a lot lighter in the pocket.

Pros: They're smaller and lighter than high-capacity players but still hold more tunes than flash-based models with the same price.

Cons: You get fewer megabytes per dollar than you do with a larger player, and these models have many of the same disadvantages of larger hard drive-based units, including the moving parts that limit physical activity and nonremovable batteries that eventually wear out and need to be replaced. Luckily, many new micro drive-based players such as the Creative Zen Micro feature a user-replaceable battery.

Flash-based players

The original MP3 player design, these have no moving parts and are known for their shockproof operation and ultracompact dimensions. Devices range in capacity from 32MB to 2GB. Creative's Nomad MuVo line, for example, includes mostly flash-based players.

Pros: Flash-based players are tiny. They also have no moving parts, so their batteries last longer, and you can jog, snowboard, or bungee jump with them without causing skipping or damage. Many flash players include lots of extra features such as voice and line-in recording, but these additions make them a little harder to use.

Cons: They have the highest per-megabyte cost and max out at 2GB.

MP3 CD players

These look just like portable CD players, except they can read data CDs filled with digital music. You can burn approximately 150 MP3 songs (10 albums) on one 650MB disc. But if you want to take your CD collection with you, no worries--these devices can play standard CDs, as well.

Pros: These are the least expensive of all types of MP3 players, and they use incredibly cheap replaceable media (CD-R/RW discs).

Cons: They're large and can skip when jostled.