I need to know how to download mp3s from a computer through USB in order to listen on my Nokia N810 device?

Thanks!

Plug the N810 into the computer with the included mini-usb cable. The builtin 2GB storage, plus any SD cards inserted into the device, will automatically appear as "Mass Storage Devices". Then just use the included software on your computer (for Windows, Windows Explorer) to copy any file(s) to your device.

Remember, before unplugging the usb cable to "Safely Remove Hardware".

How do I open these files from the built-in Media Player? They don't seem to appear in the library?

After you disconnect the cable, your *.mp3's should automatically appear in your Music Library...If not click the menu button and go to Clip->Open. You can then browse to the files.

Ok I see them now... Thanks!

Another quick question: is it possible for the Media Player to view the ID3 tags? Cause right now it's just showing the filenames.

What do you mean "view" ? It does use the ID3 tags to sort the music. Maybe you want a more powerful media player like Canola or MediaBox?

Also, you can transfer files wirelessly using SFTP. Just install openssh on the tablet, and s SFTP program on the computer (like FileZilla client), and you can drag and drop files wirelessly.

Yet another question:

Why would not the player play the files? I'm clicking the "play" button, and there's no sound? Maybe there's some restriction on the mp3 files format? (the bitrate).

And also, how can I install more powerful music player?

MP3 files should all play. The MP3 files must not be DRM-protected, obviously.

Go to http://maemo.org/downloads/OS2008/multimedia/ on your tablet and click the green "Click to install!" arrow for one of the media players there that you like. Canola2 has a nice UI and uses mplayer for playback, so it should play basically any format