I'm certainly no master, but I do rely on MP3 files to fill in the holes left by my custom audio arrangements I made to mini disk. The main reason was to add contrary vocal harmonies and make it possible to do some more guitar work, without sacrificing the rhythm section.
I use a modest PIII 600Mhz pc running win98se on the stock sound card with Roland Virtual Sound Canvas wavetable software.

This allows me to run midi files and audio files from the same output on the pc and it only takes up one (stereo)channel in the mixer.

From the explorer window (or ANY folder, for that matter) you can see about 80 song titles in front of you for immediate selection with the enter key. You can use the arrow buttons to navigate and never touch the mouse.

I still have the MD's in the car as a backup, and the HD on the PA80 is a second backup, but the pc is my "go to" machine for all things that two hands cannot do.